How Chicagoans Commute

January 23, 2014 at 3:59 pm

After the 2012 ACS (American Community Survey) 5-year estimates were released by the U.S. Census Bureau, I took to using them to find out how many people own cars in certain neighborhoods, mainly as a way to prove to some that there may be more people without cars in our neighborhoods than we think.

I used the American FactFinder to do this on an individual basis (usually by ZIP code) but found that the smaller census tracts could provide an even closer look. So I took all of the data from 2012 and I mapped it over Chicago. I used the B08141 table from the census, which shows the means of transportation to work by vehicles available, and divided each mode by the total number of workers in the given census tract to find the percentage. I also used the DP04 selected housing characteristics table to obtain the number of households within a tract, and the number of vehicles each household has. All of the data that comes from these tables can be further analyzed to dive deeper into the numbers.

I fully plan on making this map better than it is right now. I have started to compare the data to the 2000 census and I want to implement a sidebar that shows more information about the tract when it’s clicked on. Ideally we could also look at some of the nearby communities, but I focused on Chicago for just this map.

You can get a glance of the map below, or see the full-screen map here.

If you have suggestions, please comment below.

Update, 28 Jan 2014: The map now includes the functionality to turn on and off certain layers. Simply click the “Layer” icon to the left of the map to see the options.

The map can now display several layers, including one that shows where homes don't have any cars.

The map can now display several layers, including one that shows where homes don’t have any cars.

Each layer map will display the data only for that commute mode. The darker the tract, the more commuters there are using it.

You can also see a “heat map” of where the tracts with the most car-free households are. Lighter grey indicates few homes with no cars, darker grey indicates more homes with no cars, but still below the city average (~25%). Colored tracts have more car-free homes than the city average – the darker the shade, the more car-free homes. If the rate is above 50%, the tract is colored purple. The highest is 89.4%, in tract 3406 (between 35th St and Pershing Rd near US Cellular Field).

A few notes: the American Community Survey (ACS) is a yearly survey that eventually replaced the long-form census. It asks questions that go more in-depth than the decennial census, including how people get to work, how many vehicles they have at home, and so on. The kind of data that helped me make this map. Census tracts are composed of approximately 4,000 people, although they can range from 2,500 to 8,000 people. If a census tract exceeds 8,000 people, it is broken into several tracts. Like all statistical data that is based in a sample and not a population, the ACS data is subject to margin of error. The map above does not display all margins of error due to calculations I made to create the map, but future versions of the map will include more in-depth margin of error indications. Please also note that in some Census tables, bicycle commuters are lumped together with commuters who take motorcycles or taxis to work, but that in many cases bicycle riders are still the majority.