Using Lexis-Nexis, I found an estimate of 26 Christmas cards for 1990, so that the number of all holiday greeting cards would have been a bit above — probably around the 1987 level of 29 cards across all holidays. The first big drop is visible by 1994, when the number of cards received per household was about 25% lower than in 1987. There was another drop-off starting in 2003, and during the most recent years of 2007 and 2008, the number is down about 40% from the late '80s / early '90s. This does not merely reflect the fact that there are more households now than then, which would tend to lower the ratio even if the total number of cards stayed the same. In 1987, 2.856 billion holiday greeting cards were received vs. 2.117 billion in 2007 — a decrease in sheer volume of 736 million cards.
And what is the upshot?:
1) The various signals of Christmas have been steadily fading since roughly the mid-1990s, at least a decade before the "War on Christmas" debate erupted. Rather than special interests knocking off Christmas-lovers, the general public voluntarily dropped out. None of the changes in the signals is clearly related to the internet, macroeconomic indicators, etc. The only strong association I see is the larger cultural shift away from sincerity and sentimentality toward affectation and irony.
2) They have not been replaced with new signals. Rather, we're pulling out investment from the holiday altogether and shifting it into other holidays like New Year's Eve and Halloween (which Lexis-Nexis suggests was taken over by adults also in the mid-1990s). Anything that will afford us greater opportunities to make the duckface for the cameras.
Contrary to the author's suggestion, I am inclined to see the internet at work here, even if it doesn't explain the entire series. If you stay in touch by Facebook, what's the point of the yearly reminder? This is another example of how the internet can lower measured gdp yet raise welfare.
If you scroll down on the blog, you'll find other indicators of the decline of interest in Christmas.