This is a map of every person counted by the 2010 US, 2011 Canadian, and 2010 Mexican censuses. The map has 454,064,098 dots - one for each person.
I wanted an image of human settlement patterns unmediated by proxies like city boundaries, arterial roads, state lines, &c. Also, it was an interesting challenge.
The US, Canadian, and Mexican censuses, mostly. I made the map. I'm Brandon Martin-Anderson, from the MIT Media Lab. Kieran Huggins came to the rescue with spare server capacity and technical advice once this took off. Bill Morris collected and formatted data from the Mexican census.
I wrote a Python script to generate points from US Census block-level counts, and then generated the tiles with Processing. Here's more detail for the interested.
The dots are very small. Try zooming in.
The census reported that someone lived there.
The census reported that someone lives in a block which includes a lake, and that's where their dot was randomly placed. Also, some people live in the middle of lakes.