Every person gets a dot

Brandon Martin-Anderson from the MIT Media Lab created a great visualization tool showing the location of every resident of North America.


The map shows a dot representing every person counted by the 2010 U.S. Census, the 2011 Canadian Census, and the 2010 Mexican Census. There are 454,064,098 dots – one for each person.

I think the coolest thing about this map is that you can zoom in to a very detailed level and try to find your own dot (you can toggle labels on and off at the top left of the screen to help orient yourself on the map).

Although I should clarify that when I say, “your own dot,” I don’t mean it literally. The Census takes many precautions to protect personal information, so Martin-Anderson didn’t actually place a dot exactly where each person lives. He randomly placed points in each Census block to represent the total population count – the most detailed piece of information he can get – in each block.

This is evident from one of his FAQs:

Q: [Why does] this [map show that] someone lives in the middle of a lake.

A: 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.

Susan Clapp is a statistician at the University of Virginia’s Weldon Cooper Center for Public Service. She is an expert in data sources, statistical methods, and teaching us all how to understand and use data well.