You can learn a lot from satellite pictures of the earth at night; the famous picture of North and South Korea, which Tyler and I feature in Modern Principles, is just one such example.
ESRI has an interesting picture-story illustrating the lights that have turned on and those that have turned off between 2012 and 2016. It’s remarkable how much North India literally turns on in this short space of time. Lights have also turned off around the globe. Not only in places like Syria but also in much of the United States and Northern Europe. In the latter two cases, as the surprising result of more efficient lighting and campaigns to reduce light pollution. Check it out.