Finally, I used the fake Rhode Island data. So from that data, I tried all of New York City, and then New York State, and then California, too. It’s an area I know well and have mapped a bunch. I first used 2010 data to generate a dot map for Manhattan. The Census Bureau provided fake data -for some counties in Rhode Island- in the form in which they planned to release the real numbers, so we were able to build Python scripts ahead of time to ingest and process the data quickly in order to break out states, counties, places and census tracts for analysis. The release was on a Thursday at 1 p.m., and our idea was to turn it around as quickly as possible -ideally before the weekend. To prepare for the dot-density map, I spent about a week using test data and 2010 census data to determine whether I could build the national base layer quickly. The Cooper Center for Public Service made a beautiful version, as did the Washington Post.
![population density map us by census tract population density map us by census tract](https://i.redd.it/b3jnxl222u641.jpg)
The New York Times put together one I admired and explored shortly after that release (it’s broken now because it used Flash, but they built a new one in 2015). I’ve been inspired by dot-density race and ethnicity maps since the 2010 census release.
![population density map us by census tract population density map us by census tract](http://2.bp.blogspot.com/-zv_B65FqPGc/VYuRdwU6xcI/AAAAAAAAfmU/Qx9nYDu6tV4/s1600/US%2BPopulation%2BAges%2Bwith%2BBachelor%2BDegree.jpg)
The CNN Visual News team had been keeping a close watch on the census data release plans, so we knew what kinds of data we’d get and made some guesses about what we’d like to build and what other journalists at the network might need or want. We love the dot-density map he and his colleagues produced on race and ethnicity in the US, and asked John to share how they produced it within just a few hours of a major data release from the 2020 Census.
![population density map us by census tract population density map us by census tract](http://2.bp.blogspot.com/--xZ0wm4aMa4/UKw9KKGstmI/AAAAAAAAACU/79gOc0CpEWE/s1600/Population+Density,+2000.jpg)
He has a long history in data journalism, and also dedicates himself to teaching people new to the craft. John is a senior data and visuals editor at CNN specializing in climate.