Population Density vs Median Family Income

In Sunday’s “School Assignment” post, Pattsi suggested I talk to Andrew Levy at RPC. I am glad I did – Andrew was exceptionally helpful and informative and was able to deliver a rough map (NOTE: not meant to be 100% accurate) and an explanation of what he did. He even went a step further and gave me permission to post the map and quote him. He is such a swell guy! 🙂

From the mouth of Andrew Levy:

Unfortunately, there is not a simple way to obtain data and create maps when combining Census datasets such as population density and income.  American Fact Finder (http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml) does provide a mapping application, but I don’t think it will get you the detail you want.


Attached is a map that shows income ranges in different colors and density in lighter to darker shades.  Population density is available at the Census Block level while median family income is only available at the Block group level.  Please see the CCRPC website for more information about these geographies (http://www.ccrpc.org/dev/census2010.php).  Income data is from the American Community Survey which is derived from sample data.  This means that the data has inherent reliability which has been shown as hatching on the map.  Please note that the classification of population density is comparable across the four median family income levels. This is based on a “natural breaks” methodology

As you can see, lower incomes certainly have higher density patterns, though each income level has areas where population density is higher. Also note that the reliability of the data is quite varied across the community.

While this may not provide you with answers, hopefully it gives you a general idea of the conditions in the City of Champaign / Champaign School District.  Unfortunately, digging into the numbers more will introduce more error and degrade the reliability.



So even though this map is not entirely picture perfect (and not interactive and in some cases really hard to read) it at least gives us something to chew on. It is obvious that wealth is not well distributed – in some areas it seems like Green (“high wealth”) is next to Red (“low wealth”), but looking closer at the map, I think those census tracts are skewed by commercial businesses since I am fairly certain the houses in those areas are not high-end; for instance, south of University and east of Neil, or west of Prospect and between Church and I-74. As Pattsi has mentioned, if the main goal is to diversify the inhabitants of the schools, I can accept that it makes a lot of sense to first diversify the neighborhoods in which the schools reside. The problem is twofold; 1) we don’t have that right now, and 2) in order to get that, we have to get a truckload of people on the same page and build momentum to slowly get there. We are not typically patient people. The easy thing to do is have “Controlled Choice” and bus people all over God’s green earth. But that is also expensive, and as Shadow Wood is teaching us, fraught with its own difficulties.


NOTE: “Population density is available at the Census Block level while median family income is only available at the Block group level.” Be careful when looking at the map, because a large Block Group level can cover a lot of ground and may mislead you to thinking that all those homes have the same MFI – it is a gross approximation of the average income (yeah yeah, be picky about “median” vs “average”).


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