How much has the introduction of air conditioning driven interstate mobility?

Paul Krugman has had a few posts on this question, most recently this one, the first one here.  Krugman is right in asserting a major role for air conditioning, but there is a subtle framing point which is sometimes neglected.  The most on-point study is this piece from Jordan Rappaport (pdf):

U.S. residents have been moving en masse to places with nice weather. Well known is the migration towards places with warm winters, which is often attributed to the introduction of air conditioning. But people have also been moving to places with cooler, less-humid summers, which is the opposite of what is expected from the introduction of air conditioning. Nor can the movement to nice weather be primarily explained by shifting industrial composition or by elderly migration. Instead, a large portion of weather-related moves appear to be the result of an increased valuation of nice weather as a consumption amenity, probably due to broad-based rising per capita income.

Overall Rappaport concludes that “nice [warm] weather is a normal good” is the more important driving force behind the movement to the Sun Belt than is air conditioning per se, though of course air conditioning makes nice warm weather all the nicer.  Evidence from compensating differentials also indicates that “…the decreased discomfort from heat and humidity afforded by air-conditioning has not been the primary driver of the move to nice weather.” (p.26)

From 1880 to 1910, Americans overall are moving to places with bad (cold) weather.  In the 1920s they start moving, on net, to places with nicer weather and that trend has not let up.  The arrival of affordable air conditioning in the postwar era bumps this up a bit, but the main trend already was in place.  Furthermore air conditioning has been in the south for quite a while now, but migration in that direction continues.  In his second post on the topic, Krugman refers to this as a “gradual adjustment” to AC, but it seems to better fit the nice weather as a normal good story.  We’ll know more if we see this migration continuing, but I expect it will.  At some point it won’t be plausible to call the ongoing movement a “lagged response” to the introduction of air conditioning, but again it will fit the normal good story pretty smoothly.

Note also that life expectancy is notably higher in warm weather than cold weather.  Deschenes and Moretti conclude (pdf): “…The longevity gains associated with mobility from the Northeast to the Southwest account for 4% to 7% of the total gains in life expectancy experienced by the U.S. population over the past thirty years.”

That again points toward a “normal good” explanation, with air conditioning playing a supporting role.

That all said, if you look at the larger political debate going on here, Krugman is correct in arguing that lower taxes are the not main reason for this migration, even though the median voter in these states probably approves of such relatively low tax rates.  In any case, there is a clearer and better version of the weather hypothesis which can be put forward.

Addendum: David Beckworth adds commentary and some fascinating maps.


And how does this apply to businesses that move to low tax states in the south?

Did Toyota do an air con study?

Why do people move from Massachusetts to New Hampshire?

I am sure that air conditioning has been helpful in making the South/Sunbelt more habitable. I was attending a corporate meeting in Arizona in the 1990s and our tour bus guide told us about sleeping in wet sheets in order to stay cool, when she first came there from Germany after WWII. OTOH, Krugman's piece provides the usual reassurance to his loyal readers that all is well with their beliefs and those stupid (if not downright evil) right-wingers are worshipping false gods, e.g., "So when you ask why Sunbelt states have in general grown faster than those in the Northeasy, don’t credit Art Laffer; credit Willis Carrier."

Can anyone point to a current post from Krugman that deviates from progressive orthodoxy?

I wonder how many of Krugman's readers will be made aware of Beckworth's comment.

Scott Sumner has numbers comparing states within climate regions on population growth relative to whether or not states have an income taxe -- blowing Krugman completely out of the water. All that is left is splitters and an oil slick:

The Tax Foundation has number reflecting the combined personal income of migrants leaving states and entering states -- tops losers are New York and California and top gainer is Florida:

Yes - absolutely. Have you ever worked in a factory without air conditioning? It's impossible.

Besides air conditioning, Krugman should also mention the economic importance to the South of Eli Whitney inventing the cotton gin, because the cotton gin is about as relevant to current trends as is air conditioning.

It's 2015, folks.

As recently as 2002 I lived without AC (in Akron OH). AC may have been invented a good long while ago, but it's not universal even today.

None of this explains the Californians I know who now live in Florida for 1/2 year plus one day.

It also doesn't explain the rise of ISIS in the middle east. It's almost like this observation only explains certain things!

What explains your cluelessness re the explanatory rivals Krugman pretends to be adjudicating between?

What explains your casual assumption that a couple of people you know (who are highly likely to be fictional in any case, since the laws about residence don't work that way in California) represent some kind of trend?

Never mind, the answer to that is self-evident.

The demographic statistics on out-migration from California are there for any MR troll to look up on Google.

Why is Illinois losing jobs and Indiana is gaining them? Why is Idaho gaining in polulation and New Mexico is losing population? Why did GDP per capital go up in Singapore by factors of 10x over those of Vietnam, Malaysia, Venezuela & Indonesia? The examples explode the presumption that air conditioning vs latitude is somehow the great causal factor controlling of economic and population change since 1960.

And how about the tens of millions from Latin America who have come north -- are they coming to the cooler north because of the rise of air conditioning?

I think part of it might be the fact that many of the things you mention are not actually happening.

For example, here's the population growth in New Mexico over time:

Again, read Krugman and his cherry picked calendar dates, and compare also what's happening in last year or so. Idaho outstrips New Mexico in both comparison periods.

I know all sorts of businesses and people who have moved from coastal California to Texas, Idaho, Colorado & Nevada & I can tell you they did not do it for the warmer weather & AC -- and this isn't merely anecdotal, countless studies show a significant migration of native-born businesses and individuals moving out of California and to other states.

Buck Knives, San Diego, CA, 1947-2005; Post Falls, Idaho, 2005-present.

Ha! They'll be sorry once we have high-speed rail down the heavily-travelled Merced-Bakersfield corridor. Imagine that! 90 minutes from downtown Merced to downtown Bakersfield! We'll see an economic boom like nothing that has come before!

You jest, but did you know that the capital of France is described by one and all as the "Bakersfield of Europe"?

Here is the canary in the coal mine -- why have native-born Californians left the state? And why have so many businesses left California?

These weather explanations are dead in arrival as no state has weather that can touch California.

Hawaii has milder summers and milder winters.

Right Mark, and I imagine you feel that Miami has milder summers than CA too. Which isn't really relevant anyway... bringing up Hawaii is like bringing up American Somoa. (No offense to Somoans)

Hawaii is more affluent than American Samoa by a factor of about 5. The trouble with Hawaii is that if you're not suitable for rural or small town life (with the circumscribed occupational profile such loci have), you live in greater Honolulu. Greater Honolulu has a population of about 800,000, so it's a midsize city. Housing costs can poleax you and even quite affluent people eschew detached housing for condominiums. It has extraordinary air in terms of temperature and (in the right loci) scents. However, the trade winds can come to annoy you and deciduous flora planted in Hawaii look awful due to the effect of trade winds on their growth. The whole town is ticky-tacky and antagonistic to pedestrians. Honolulu is a city without character in its built environment, a city of high rise dwellers, a city where the local university is a punch line. The Japanese locals have their own signature sensibility and are at home in Honolulu in a way they cannot be elsewhere. That's not you. You'll fall into a social network of haolies who've migrated from elsewhere, inhabitants but not truly citizens.

Honolulu traffic is also horrible.

What's relevant is an absolute truth, uttered by Truman Capote: "you lose one point off your IQ for every year you stay in California".

Happened to Richard Feynman .

Nice weather expanded - a lot of people moved into and stayed in the American midwest and north east for economic reasons. Farm land. Iron Ore. Heavy industry.

When those constraints on economic life are removed, people and businesses are much more free to locate based on weather, local character, taxes, services, and so on. We see a lot of this in Seattle - Microsoft and Amazon could both be located literally anywhere in the 1st world. Boeing has never been tied to iron ore or coal. And of course service professions which are an ever growing part of the economy can be practiced in any active market.

In addition, some number of the places with nice weather are notable for also being very beautiful. Parts of the midwest and north east are remarkable for being boring or ugly as well as having very bad weather.

The notion that Seattle has a nice climate seems odd to a Californian like me, or for that matter, to Bill Gates, who spends his winters in Rancho Santa Fe in North San Diego County.

Seattle has nice climate....for exactly 3 months in the summer. After that, it's "bye bye Sun; see you next year". Especially for someone who has spent many years in a place like Los Angeles (as I did), the Seattle climate can drive one to depression. I left after 2 years.

It's been 60 and sunny 9 out of every ten days since January. We had 75 degrees on a day where boston got four feet of snow.

Guess climate change has impacted the PNW after all! I was there 2008-2011, and most days outside mid June-mid September were overcast. I recall a period during the fall (I think October-November 2009) when I didn't see the sun at all for a month or so. It made me deeply miss Southern California.

It's nice compared to Buffalo.

If Americans had the sense to take more holidays in return for a lower salary, then those in the miserable states could take a couple of sunshine breaks in the winter.

I am an hour and a half from Buffalo. After a ridiculously cold second half of winter, I am absolutely planning to spend a month in the middle of next winter elsewhere.

If they had a lower salary, then how could they afford a vacation. I guess that could to what Europeans have done and stop having children but how many Americans can to give up children and grandchildren in order to sit on a beach in winter?

Very few people live in the miserable states, and those there are selected from among those whose sense of well being is insensitive to physiography and climate. The thought of living in South Dakota is disturbing to me, but the people who live there like it well enough.

Buffalo has had trouble finding it's way. Western New York (which encompasses greater Buffalo and rural areas and small towns tributary to it) has had since 1980 population losses of 8% of the total at a time when the rest of Upstate was holding it's own and the national population increased by 36%; maybe, just maybe, the population therein has stabilized in recent years. During it's heydey, the city had some agreeable social features ("Everyone pretty much had the same kind of job and made the same kind of money" quoth Gregg Easterbrook), but it was unpleasant aesthetically. You could smell the air all the way to Niagara Falls. The emphasis on heavy industry also meant a lot of fires. Tlhe adventures of the 'battling blazebusters' was supposedly a daily feature on local television. The juxtaposition of the city vis a vis Lake Erie means masses of lake effect snow you see much less of in Rochester and Syracuse. So, the winters can be difficult, though they do have the equipment to cope with them. Also, Upstate cities did not go to school with William Bratton the way NYC did, so the homicide rate in the Buffalo municipality is about half-again what it averages in NYC slums and 2.5x what it is in Harlem.

Rochester and Syracuse both get lake effect snow off Lake Ontario, when the wind is from the northwest.

They get the lake effect snow, just 30-40" less of it in a typical year.

They still get a lot more snow than most places in the lower 48 do-- including other northern cities.

You have something with Buffalo, huh? I think this is at least the second time you've called it out as a shithole. For someone from across the pond, it seems a little weird. Is this based on what you've read about the city, or have you spent a lot of crappy time there or something?

The utility of Seattle is that the only Californians there are those who could not abide California.

The relevant comparison is not Southern CA. It is the median climate.

The daughter of one of my former co-workers worked for a saltwater aquarium specialist several years ago, and ended up maintaining the aquarium in Bill Gates' house in RSF (of course, applying the term "house" to a dwelling in RSF is like calling a Patek Phillipe a "wristwatch"). Rancho Santa Fe is the place that the rich and famous go to be rich and not noticed; in fact, the locals in San Diego's coastal North County consider it rude as well as gauche to gawk at the part-time residents like Gates.

Amusingly, this insight was arrived at by Lee Kuan Yew (whose state funeral was just conducted here in Singapore). Asked for his opinion about the greatest invention of all time, he declined to name the wheel, the printing press, or any of the usual suspects, opting instead for:

"Air conditioning. Air conditioning was a most important invention for us, perhaps one of the signal inventions of history. It changed the nature of civilization by making development possible in the tropics.

"Without air conditioning you can work only in the cool early-morning hours or at dusk. The first thing I did upon becoming prime minister was to install air conditioners in buildings where the civil service worked. This was key to public efficiency."

This is true of office work. A desk job is pure torture in muggy humid conditions without AC, especially when power failures are a fact of life (that's how I grew up in India; not doing a desk job, of course, but studying at home or school was not very comfortable in the summer months.)

But I don't think tropical weather impacts most other (non-office) work. People have been farming throughout the tropics since antiquity, and I know of no study which indicates that agricultural productivity in the tropics was any lower than in temperate regions. Seasons are more relevant here: it is not possible to work outdoors in the cold season in temperate regions whereas productivity is low (though not zero) in a tropical summer. Yearly productivity probably comes out to be the same.

Irish economist and dairy farmer Raymond Crotty pointed out that without the lactose tolerance mutation making adult milk-drinking feasible, places like Ireland, Denmark and Switzerland (due to the higher altitude) would have been only marginally habitable for agriculturalists.

So did these places in NW Europe not have much in the way of agriculture before the Indo-Europeans made their entry? Or were the pre-IE populations already lactose tolerant?

A lot of research is being published on that question this year, so I'm going to wait for the dust to clear before venturing an opinion.

To the best of our knowledge farming was initially brought to Neolithic Europe by migrants out of Anatolia. We have no written records from those people, but there's some indication that they were related genetically to the later Indoeuropean-- the latter being a branch of their ethic group who had migrated north onto the steppe, perhaps after the Bosphoros re-opened and flooded the Black Sea basin.
It's also fairly certain (via genetic and linguistic studies) that the Indoeuropeans did not replace the people of Europe, but merged with them, for the most part peaceably (the only indication of warfare during the IE migration period is in the Balkans.)

"it is not possible to work outdoors in the cold season in temperate regions": not so. In fact "temperate" means roughly that you can work outdoors in much of the winter. It's continental climates where feet of snow would keep you from working.

By "temperate", I meant the broader Temperate Zones of the planet. As you right point out, climate in these zones varies widely (especially if Mediterranean climes are considered temperate). As per my understanding, temperate regions are those in which winters are not cold enough to make life impossible (i.e., it's not the tundra) but they are cold enough to do any productive outdoor work (e.g., can't grow food if the temperature is between 0 and 5 degrees Centigrade, but people can live comfortably with suitable clothing.)

Lee was an amazingly quotable man.

I suspect it was the odd combination of being a native English speaker in a Chinese milieu that gave him the courage to be Captain Obvious.

The density of cities in the US is possible due to air conditioning. ASHRAE put out a series of videos a few years ago describing the architectural changes made possible by air conditioning.

I think air conditioning is an enabling technology. It will not produce jobs by itself, but makes places like Houston or Singapore livable. Both those cities would (and did) exist without air conditioning, but they could not have risen to their current stature without it.

Texas, especially Houston, where I grew up, is by no definition nice weather. I think the economy there would be dramatically different were there no air conditioning. Hard to tease all of the inputs apart, but could you imagine trying to run Mission Control with no A/C? Good lord.

In the early 20th Century, British officials assigned to the consulate in Houston, TX received the same Hardship Pay bonus on their salary as officials sent to Lagos.

Britain was rather well run in those days.

There's a crew of relations in my nexus who've migrated from Virginia to Texas. The Virginia partisan in the family quoted a Civil War general to one of them, "If I owned both Hell and Texas, I'd live in Hell and rent out Texas".

Why in the world is Houston a bigger draw than San Diego?

The AC doesn't account for it.

Oil is only a part of the draw to Youston.
A key piece of evidence is in a name: The JOHNSON Space Center. Good ole LBJ extracted that NASA investment as a trade-off to support other votes.

I'm sure the Johnson Space Center and extractive industries (which employ about 3% of the population in the generic locale) can account for the presence of a city of 5 million on the Gulf of Mexico.

Is the Johnson Space Center expanding? Seems like its been there quite a while so how would you explain current growth?

Because all of the buildable land within commute distance to San Diego is already built on?

Exactly the comment I was going to write. San Diego (and Orange County as well) have a great climate, lots of natural beauty, the opposite of Houston. But the terrain in coastal SoCal (excluding the LA basin) puts a lot of limits on buildable land, and in San Diego county, the government has snatched up a huge amount of prime real estate (Camp Pendleton and MCAS Miramar, plus huge chunks of the San Diego bay). Houston's housing is at least a factor of two cheaper than comparable housing in San Diego.

San Diego is a much more expensive place to live. Can we correct for that without removing the impact of taxes? If so, does the difference remain?

This makes sense to me. I am not sure why other evidence of moving, e.g., from California, etc., counters this claim. Weather is one element of a bundle of goods being chosen.

Krugman has a single-cause explanation with a minor causal modifier. The air conditioner & escaping cold weather are suppose to do all the work, shutting down anything said by anyone else about regulations, taxes, price controls or ease of doing business.

Texas has been well-air conditioned for a half century or more. Tom Wolfe's 1977 book about the Mercury astronauts, "The Right Stuff," is largely set in Houston about 55 years ago, and there are numerous references to various places being "air-conditioned Texas-style, that is: within an inch of your life." John Glenn and Co. are constantly trying to work the cricks out of their necks that are caused by the icy blast of the central air conditioning.

So the advent of AC doesn't obviously account for the economic performance of Texas in recent years, since it has had AC for a long time before.

How practical was it to have residential AC back then? I don't know how high purchase and electric costs were for AC back then. AC today is far more efficient than it used to be.

What I mean to ask is, how many Houstonians actually had central AC 50 years ago?

My grandparents purchased a mess of window units ca. 1955.

One thing I think people neglect is that building practices used to take more account of local climate, so A/C ended up substituting for earlier practices and represented less of a net gain in comfort than it would appear, as inappropriate architectural styles were imported or generated. This is true in the north as well as the south. If you've got cross ventilation, you can get along with just fans in large swaths of the country.

Spot on. To posit that "Krugman is correct in arguing that lower taxes are the not main reason for this migration" is remarkably blinkered.

what is amazing about all you krug bashers
he has some *data* (you know, numbers and stuff) about the increase in AC...
and you guys have your gut,and an anecdote and some relatives...but you are sure that krugman is simplistic !!

Krug has data that a/c is a technology that saw increasing usage, yes.

The rest of his posts are attempts at getting his readers to believe something stupid without himself getting caught saying something blatantly stupid.

I love it. Corporations do tax inversions. The rich evidently lobby (spend $$$) to lower their tax rates. Wealthy individuals go to great lengths to lower their tax incidence. But, moving out of NYC or CA? Unpossible!

Before air conditioning was the electric fan. It made warm climates much more endurable. Here's a history of fans:

When we lived in South Australia we didn't bother with A/C. We did have ceiling fans, though. Wonderful things: they let you sleep soundly. That was in a desert's edge Mediterranean climate, so like much of California.

And of course the traditional dress code was shorts and knee socks.

In Holland, many of the building use positive pressure mechanical ventilation. This ensures a constant airflow all day long.

Not very effective in humid areas like the American South.

People don't spend as much time outside these days, so perhaps the premium for California-like climates will decline.

AC is just part of the picture. There's a conscious effort being made to structure the surrounding environment in every way. The ambient temperature must be 73F, there can't be any odd, not to say unpleasant, odors, noise, ie. ambient sound, must be a product of the music industry, perceived ugliness must be covered. If a person leaves their air-conditioned home, rides in an air-conditioned limo with Steve Perry singing on the CD player, jumps on a Airbus 320 to Nairobi, gets in a limo that drops him off at the air -conditioned Serengeti Wildlife Observation Center where he can look at lions from an air-conditioned deck while Yanni plays on the PA system and return the same way, has he actually been to Africa?

It's all that effing "music" that would kill me. I refuse to use supermarkets that play that filth at me. In fact, even if they played decent music, I'd still dislike it. Other people's choice of music, forced on me when I'm not in the mood, is deeply unpleasant.

Amen, amen, amen: death to non-diegetic music, everywhere and always (especially in advertising and even more especially in all news programming over radios and televisions).

My favorite grocery store played Ratpack 24/7, save December. I quite loved it, especially the produce section that filled half the square footage and had 50 different kinds of apples.

I do not understand why sweating balls is considered "nice" weather. Insane people.

"From 1880 to 1910, Americans overall are moving to places with bad (cold) weather."

When did coal or gas powered central heating become practical? My impression is that middle class homes in the North were pretty cozy in winter by, at least, the late 19th Century.

Summers, however, were pretty miserable even as far north as Chicago. My father lived from 1917-1929 in Oak Park, IL, about ten miles west of Lake Michigan. The prevailing winds in the Chicago area are, roughly, from the west, so the lake only cools a couple of miles inland. (When I lived in Chicago, I always lived within a few blocks of the lakefront to avoid the more continental climate prevailing west of Ashland Avenue.) Hence, my father's family spent their summers in on Michigan on the opposite shore of Lake Michigan from Chicago, with my grandfather taking the ferry from Navy Pier each weekend to join them. Western Michigan is nicely cooled by the prevailing wind blowing across the lake. (But it gets a lot of Lake Effect snow in winter.)

I think it was more common in the past for the upper middle class to "summer" somewhere cool. For example, the 1955 Marilyn Monroe movie "The Seven Year Itch" is premised on the idea that it was extremely common for the wife and kids to spend the summer at the beach or mountains, while the husband stayed in Manhattan and worked. The huge wealth of New York means that's still somewhat common despite the enormous cost of Hamptons real estate today, but I suspect this pattern was more common in the rest of the country than it is now when most middle class families have air conditioning.

For example, in recent years, much of the country has switched to starting school in August rather than September so that the fall semester can be over by the long Christmas holiday. But this presumes that schools are air-conditioned, which was not that common even a generation ago.

Rice U. in Houston was something of a pioneer in the modern schedule of starting the Fall Semester a week before Labor Day in August. But one year when I was at Rice (perhaps August 1978), the air conditioning failed for about 3 days in the Sid Richardson dormitory highrise. The heat and humidity was tremendously horrible since nobody owned a fan and the windows couldn't even be owned in that extraordinarily ugly example of modernist architecture.

A minor point. Schools in the southeast were nearly all air conditioned pre-1980. So close to 40 years.

And honestly I have no idea how anybody learned anything during the hot days before air conditioning. My ability to learn in a class room setting at temperatures above 32C/90F are minimal.

Minor point to Minor point: Vanderbilt University in the early '70's: only the newer Chemistry building was air conditioned. None of the older buildings in the College of Arts & Science had it.

The huge wealth of New York means that’s still somewhat common despite the enormous cost of Hamptons real estate today

About 120,000 people live in the low-density townships on the end of Long Island. The dense settlement Downstate contains 12,000,000 people, with another 5.7 million over the river in New Jersey. Not that common.

No, you are misinterpreting what I said. A much higher fraction of people who are legally resident in Manhattan use "summer" as a verb than in most other places in the country. So, the "Seven Year Itch" lifestyle of my father's moderately affluent family in Oak Park, IL in the 1920s is largely obsolete in Oak Park and most of the rest of the country due to air conditioning and other changes. Thus, when my father and I drove from Chicago to the west coast of Michigan in 1983 to look for his old summer cabin, this attractive coastline was not doing all that well economically because Chicagoans could stay home in air conditioned comfort.

But summering carries on in Manhattan, which notably empties out on summer weekends and in August with wealthy locals heading for the Hamptons.

iirc, Mencken mentions that all summer, the stench from Chesapeake bay made Baltimore unbearable

The new dorms at George Mason are air conditioned. First time I ever saw that.

Cowan and Rappaport are too young to remember what it was like living in the South before air conditioning; indeed, they've never really lived in the South (not the deep South anyway) where summers last 10 months of the year. They are also too young to remember a time before the interstate highway system, which meant driving from place to place on two lane highways (even into Atlanta!). It's the combination of air conditioning and the interstate highway system (thanks Ike) that opened up the South to mass migration of people of all ages to the South. Sure, air conditioning was invented and available "for quite awhile now", but people in the South were mostly poor and air conditioning was a luxury that few could afford; and even those who could afford air conditioning (like my parents) considered it an unnecessary luxury. My impression is that Cowan and Rappaport are so committed to beggar thy neighbor tax policies for all that's good in the world that they can deny that the weather or roads (roads paid for by the evil federal government) matter.

Public buildings such as restaurants and stores were the first to have air conditioning. Restaurants and stores with air conditioning had little signs on the window that read "Come On In It's Cool Inside", spoken by the figure of a penguin. These little signs were as ubiquitous as painted metal roofs that read "See Rock City" and billboards that read "Impeach Earl Warren".

Notwithstanding our pleas, our father never took us to see Rock City, which in our imaginations was a city and all its buildings made entirely of rock. As to our questions to our father about Earl Warren ("who is Earl Warren", "what does impeach mean", and "why do people want to impeach him"), I never really understood what all the fuss was about - something to do with "colored people".

How much of the golden era of movies was due to the proliferation of air conditioned theatres?

I'm sure it had a big part. I remember as a kid in the 1960's walking out of a movie theater and being hit by the blast of hot air. It was like opening the door on an oven. It made you want to go back inside.

Everyone loves the fabulous interstate highway system, the covering with concrete of many thousands of acres of otherwise productive property, the separation of neighbors by impassible concrete barriers, the continuing investment in an infrastructure that makes cross-country travel for any reason possible 24/7. Obviously, even more miles of interstate highway are needed for maximum development. Getting from point A to point B is what's important, not what happens when one gets there.

Electricity... it kills people!

the covering with concrete of many thousands of acres of otherwise productive property,

There are, I believe, about 38,000 linear miles of Interstate Highways. The width is variable, but six lanes with a median will seldom extend more than about 160 feet, or 0.03 miles. So, 1200 square miles would be a passable estimate for the area covered by asphalt. I believe there were about 800,000 sq. miles of arable land in this country in 1950 (and, of course, much of the Interstate milage cut through meadow, ranch land, and waste land.

I do not love the Interstate system, it's a thing of utility for the vast majority; it needs to be subject to tolls, just as bus rides are. The injuries it did to cityscapes were an aspect of bad urban planning, not the cause of bad urban planning. The effect of Interstates on the quality of the cityscape is mild compared to strip mall development.

You can get both in Houston! But everything's air conditioned!

Thank you
The inca made it a capital offense to build on arable land

They call them "freeways" to denote the absence of feeling or emotion

That concrete barriers kill neighbor hoods most people don't get cause they don't live in a neighbor hood

Walmart etc give us low cost stuff, but the trade off is that you have to drive 20 or 30 minutes, instead of walking to your neighborhood store...did anyone note that walking is a best exercise, and having people on the street is good ?

why is it that when "liberal" economists like krugman talk about infrastructure, ti means more cars and highways
why doesn't it mean more mass transit ?

Because people's time is valuable.

"That all said, if you look at the larger political debate going on here, Krugman is correct in arguing that lower taxes are the not main reason for this migration, even though the median voter in these states probably approves of such relatively low tax rates."

Perhaps not lower taxes directly (though there is certainly some of that -- snowbirds establishing their domicile in Florida for tax reasons). But indirectly? Of course. People relocate for economic opportunities, and those have been expanding where taxes and regulations are lighter. As others have pointed out, approximately nobody moves to Houston for the 'nice' weather.

As a resident of Western New York, I find it hard to believe that good weather and lower taxes could both cause people to move elsewhere. I suspect some kind of mass delusion is at play instead.

Standard US economic history has attributed higher growth in the US South to three variabes: spread of AC, spread of interstate highways, and passage of civil rights legislation leading to improved race relations. Why is it that this current outburst of discussion of this issue is leaving out this third factor?

Because the South tends to vote Republican, and Republicans are evil racists, so there is no way relations have improved between evil Republican southerners and black people.

Because of the possibility that it's PC rodomontade? The effects of PC are so widespread and insidious that people may begin to see its evil effects even where they are absent.

Blacks moving from the north to the south doesn't fit the liberal narrative.

and passage of civil rights legislation leading to improved race relations. Why is it that this current outburst of discussion of this issue is leaving out this third factor?

Just to point out that the most severe impediment to congenial race relations was the corruption of the police and court system. A metric of that might be the frequency of lynchings. The thing is, lynching was a phenomenon in almost monotonic decline from 1893 forward and had nearly disappeared by 1946. Re-enfranchisement of Southern blacks dates proceeded from 1945 to 1960 without any legislation, and even in a state like Louisiana, 20% of voting-aged blacks had managed by 1959 to register without any federal legislation assisting (the share having been 3% in 1948). The most obtrusive sort of legislation prior to 1964 consisted of judicial decrees applied to school systems. The notion that that improved race relations is debatable. Public accomodations law had some congenial effects...and some unfortunate downstream consequences. Employment discrimination law was great, if you wanted the task of sorting the labor market dominated by lawyers; not sure what effect that has on 'race relations'.

Segregation in commercial establishments (e.g., lunch counters) was an expensive, inefficient system of government-imposed regulations that businesses got rid of quickly when the political-social climate changed a half century ago.

Ending the economically inefficient Jim Crow caste system did much for Southern prosperity, but that happened a long time ago, seeing as how it's now 2015.

Another boost to prosperity was Southerners getting over Pickett's Charge falling just short so they stopped sitting around like characters in a Tennessee Williams.

One reason Texas was so much more economically dynamic than the rest of the South in the first two-thirds of the 20th Century was that Texans didn't care much about losing the Civil War. (They had the Alamo-San Jacinto.) Texas tended to attract Southerners who were sick of hearing about the Glorious Cause and wanted instead to get on in life.

Add right-to-work laws to the list.

Two kinds of a/c: process and comfort. Most comments are about comfort. But you can't manufacture many products, from electronics to pharma to textiles, in most areas of the South year-round without a/c. There's no "cloud" without a/c. It's process that drove the migration. Feeling comfortable was just an added bonus. Willis Carrier started in a printing plant, not a front office. (See "Weathermakers to the World")

That's an excellent point. Many modern factories wouldn't be tolerable without A/C. Also, Personal Computers would lose their hard drives on hot days.

I came into a plant one July Saturday morning during a production shut down. It was 9am and I immediately noticed that it was hot. I asked when they had shut down the A/C and was told they shut the power down the previous evening. I asked if anyone had shut down the operator terminals and oops the local plant engineer hadn't thought about it. Six of 30 had hard drive failures before we got to them.

so corporate decides it is a mission critical server
Redundant hot swappable everything, redundant ACs, temperature monitors tied to a phone , with like 8 people that get called if the temperature spikes.
sys admin comes in on monday, AC is down, server is fried.
"they" forgot to put a power backup on the phone.

The best academic piece written is still Ray Arsenault's "The End of the Long, Hot Summer."

I moved to Tucson AZ from the northeast 10 years ago after retirement. I am surrounded by people who did the same. The two great enablers for my move are A/C and a reliable water supply. Water supply is now under threat and could have a major impact on future movements into this region.

The key research on migration and AC was done by my colleague at MSU, Jeff Biddle.

“Air Conditioning, Migration, and Climate Related Wage and Rent Differentials” Research in Economic History, vol. 28, 2012.

"Making Consumers Comfortable: The Early Decades of Air Conditioning in the US", Journal of Economic History, vol. 71, 2011.

“Explaining the Spread of Residential Air Conditioning, 1955-1980.” Explorations in Economic History 45, Sept. 2008.

I'm sure the advent of AC was a big factor in people moving south decades ago, but its explanatory power now for interstate migration seems pretty marginal. Meanwhile, I'll note this NYT piece from a few years ago which highlighted the movement of black New Yorkers down south:

Beyond the improvement in the racial situation, reasons offered for moving typically had to do with greater affordability and employment opportunities. But I don't think that comports with Krugman's preferred narrative.

The migratory patterns seem like data in support of global warming (as in this lid revealing preferences that people actually prefer a world warmer than the one we currently have)

In our search for monocausal explanations such as hotter climates being normal goods, let's remember that everything is always changing simultaneously, and this is particularly true in industrializing countries. A lot happened in the USA during the time periods in question; for example, the eradication of hookworm and malaria in the South, among many other triumphs of public health.

Those would certainly be relevant to the pre-WW2 era. But really can't be too big a factor in the last 50+ years.

Hats off, gentlemen and ladies. The chat on this thread has been far more interesting than on many others.

The single best factor I can find to predict population movement is whether or not the state has a right-to-work law. Jobs move to RTW states, and population follows the jobs.

it is easy to forget that malaria was not eliminated from the south east until 1951. This was a significant deterrent to settlement. Again, it was a program led by the Federal government which was responsible.

I grew up in Miami! in the 40's and 50's. No AC. Not at home, not at school, not on public transit. You get used to it sort of. In the summer everything made with leather turned green from mold. In college no AC, not in classrooms, not in dorms. Sort of tolerable except on some nights with a dewpoint of 80 and a low of 82. The only relief a Dutch Wife (look it up). Even worse the mosquitos and palmetto bugs multiplied and attacked.

I would not trade it for today if I could. No crowds like now. Lots of unspoiled nature. Lounge lizards confined to Miami Beach. Only high class latinos. Those were indeed the days.

Greater Miami had in 1950 a population of about 550,000, about a tenth of what it is today (and similar to Hartford, Ct. or Dayton, Oh in our own time). As recently as 1940, Florida was the least populous Southern state, bar West Virginia. It had around 2 million residents.

I'm surprised no one has mentioned the most glaring flaw in Krugman's articles. He keeps citing total population growth without differentiating between growth due to demographics/birth rates vs. growth due to migration. Lumping both of these things together doesn't really tell you anything. California, for example, has had relatively high population growth even as more people have been moving out of the state than in for years.

California is nice but I'll take a place like Chicago with plenty of fresh water. Water really makes a difference as the west coasters can testify.

My first 4 years after leaving home was without AC. I drank a lot of ice water. Really helps.

AC helps make the Houston climate as tolerable as the Chicago climate.

Then it becomes a question of where you'd prefer to live. Blue state or Red state?

People seem to prefer Red State

That rather seriously misrepresents the choice.

There are a number of factors that are likely to be involved in migrations.
1) Employment
2) Affordability
3) Climate
4) Cultural reasons
5) Regulatory/Political environment
6) Income Maximization

As best I can tell the first two are probably the main drivers of migrations inside the US. The fourth doesn't seem to be driving a large migration at the moment, though it might be significant for Salt Lake City. The fifth seems to be marginal for individuals and the sixth even more so.

Returning to that third broad factor. Before AC Chicago had hot summers and snow in the winter. Houston had nice winters, but had long miserable summers. After AC Chicago still has snowy winters, but in Houston you can mostly avoid the miserable summer weather. This makes Houston's overall climate significantly nicer than Chicago's.

Power steering and air conditioning are the two efficient causes of the so-called women's liberation movement.

Washing Machines, The birth control Pill ??

Reality Check:
Dislike for Paul Krugman aside, does anyone actually believe that the rise of the south from a poverty stricken rural backwater did not depend, heavily, on AC ?
Are people actually arguing that it there was not widespread residential AC, the south would be where it is today ?
I'm sorry, I know one shouldn't rely on "common sense" and gut feeling, but I'm having a hard time with this

not to say things like trample poor people laws (aka RTW) and lack of public health depts and so forth aren't important; but to argue that mass migration to MI or GA would have occured without AC ?? really ??

Who is arguing that?

I think people are arguing that it's 2015.

The awareness that air conditioning made Houston's prosperity possible was already the conventional wisdom when I arrived at Rice U. 39 years ago, so Krugman should be looking at other factors to explain more recent eras.

In 1940 there were 3 million people living in Georgia, 2.1 million in Mississippi (MI is Michigan). In fact, as a proportion of the country, Mississippi has significantly *de*populated since the invention of air conditioning. Again, someone who is - I'll assume -- used to 15 degree winters can't fathom the idea that people might be able to survive in warm climates without withering away.

I'd imagine that defeating yellow fever was probably a significantly bigger impetus for people moving south. But that wouldn't even cross most of our minds.

Yankees, in general, seem to have a hard time understanding that it's possible to survive without air conditioning. I think Krugman is committing the fallacy of assuming that his own preferences ("I couldn't imagine living somewhere muggy!") are universal.

His other fallacy is assuming that recent growth trends are primarily attributable to an invention of 60 years ago.

Re: Note also that life expectancy is notably higher in warm weather than cold weather.

I assume that must be a modern trend (at least insofar as we are talking about fairly temperate climates in both cases). In past eras areas with hot summers and prolonged warmth were associated with increased morbidity from insect-vector diseases, notably malaria. In this regard mosquito control, antibiotics and modern sanitation in general made warm weather areas more habitable.

1880-1910 people were not moving toward bad weather, they were moving away from malaria. Once southerners understood its' cause they could fight it. With the aid of DDT they finally vanquished it after WWII and the great migration began.

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