Anticipating Chicago's Demographic Trends

The narrative surrounding the 2020 US Census is that the Midwest and Northeast will experience a decline in population relative to the Sun Belt and the West. Chicago, and the Chicagoland area more generally, is often cited as a city from the Midwest that will experience a relative population decline in the 2020 Census, affecting the state of Illinois' representation in the federal government. Estimates provided by the US Census Bureau through the American Community Survey (ACS) can provide insight into the population change in Chicago. The 2018 5-year ACS provides estimates in population at varying levels in the United States over the 2014-2018 time period. The ACS provides data that can go beyond the county level as the Bureau's most detailed published estimates for each individual year are at the county level. However, the ACS does not contain a fixed date for its estimates; rather, the estimates fall within the 5-year span. That said, the ACS can provide insights within a smaller geographic footprint by estimating data at a tract level rather than limiting the data to the county level. The Census Bureau defines tracts as small subdivisions within each county that are between 1,200 and 8,000 inhabitants, averaging 4,000 inhabitants per tract. 

The ACS does not provide data at a city level per se, but in tracts that are separated by county. To use the ACS tract-level data, the Cook County tracts must be limited to Chicago itself. As shown below, this can be done by using spatial vector functions in R. This does not allow the data to be limited to strictly Chicago, as some Cook County tracts straddle both Chicago and other areas that lie within the county but, for this analysis it will suffice. 

The 801 census tracts that make up Chicago are too overwhelming to make sense of when discussing subsets of Chicago. Using data available on The Chicago Data Portal, the tracts can be combined into defined Community Areas with further use of spatial functions in R. The 77 Community Areas are much easier to understand visually than the 801 tract groups. The US Census Bureau's published boundaries do not exactly overlap with the city or its Community areas as shown below, but again, it is appropriate for analysis. 

Most of the population growth occurred in and around the Loop as well as the northern part of the city, while most of the population decreases occurred in the south and western parts of the city. With the previously stated caveats regarding city boundaries and the fact that the 2018 5-year ACS figures are estimates, the overall population of the increased slightly with an increase of .8%. 

Four community areas declined by roughly 20% percent whereas the rest of the community areas with population decreases contributed more modestly.  Only one community area increased by more 20%, which was the Loop at 28.6%; however, the change in population in community areas with an increased population was spread more evenly than in areas with population decreases. 

Restricting the plot to only show areas with population changes of greater than ±10% shows that the most significant community area population decreases were indeed in the South Side (Burnside, Fuller Park) or the Southwest Side (Englewood, West Englewood). The areas with the most significant population growth were in the Central (Loop, Near North, Near South), adjacent to the Central (Douglas, Near West Side, Oakland), the North Side (North Center), or on the very edges of the city (Clearing, Riverdale). A breakdown of which community areas fall within each side can be viewed here.

The North Side and Central areas that have experienced the most growth also tend to have higher per capita incomes. The Near North Side ($96,661), Near South Side ($85,146), Loop ($79,779), and North Center ($70,550) areas had four of the five highest per capita incomes in Chicago and are well above Chicago's per capita income of $34,750. These areas also had population increases of greater than 10%. Higher per capita incomes suggests that many of the people who live in these areas are young professionals, given that children and the elderly contribute less to per capita income as they are less likely to be employeed

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The opposite cannot be said for the areas with the lowest per capita income. Curiously, Riverdale had the lowest per capita income at $12,215 even with it's 12% increase in population. However, Englewood ($14,410),  New City ($14,410), West Englewood ($15,865), and Fuller Park ($16,134) had the 7th, 8th, 11th, and 12th lowest per capital incomes, respectively.  The fact that these areas had lower per capita incomes does support the idea that the areas with increasing population have a higher income and areas with decreasing populations tend to have a lower per capital income. 

Many of the community areas have per capita incomes that are on the lower end of the distribution. The areas with higher per capita incomes are the ones that stand out, and those areas do tend to have higher growth. The trendline is significantly influence by those areas with higher per capita incomes. It would be safe to say that the ares with higher per capita income tend to have a population increase, as all but one of the community areas with a per capita income above average had an increase in population.

It appears that the community areas that have a higher increase in population and a higher per capita income tend to have a higher proportion of people who identify as White. At the very least, the areas that had the largest population decreases tend to have a much lower percentage of White individuals. 

The community areas that had the largest decrease in population, those in the Southwest and South Side, tend to have a much higher proportion of Black or African American individuals than the rest of the city. Riverdale is a notable exception, in that it had a higher increase in population (12%), yet it has a very higher proportion of Black or African American individuals with 96%. Sadly, Riverdale also stood out for having a lower per capita income despite its higher increase in population. Likewise, Oakland (92%) and Douglas (68%) have a high proportion of Black or African American individuals, high increases in population, but lower per capita incomes. 

There does not appear to be any community areas that saw a large decrease in population that with a high proportion of Hispanic or Latino individuals, as the majority of Hispanics or Latinos are primarily located in the western parts of the city. Most areas with a large proportion of Hispanic or Latino individuals saw either moderate increases or decreases in population; however, the Clearing community area is 57.7% Hispanic or Latino and a population increase of 11.2%. Although Clearing did not see the largest increase in population, nor is it one of the areas with the highest proportion of Hispanic or Latino individuals it is the most notable combination of both. Likewise, two other areas with large Hispanic or Latino populations that had sizable population increases were West Elsdon (6.8%) and East Side (5.2%) with the areas consisting of 81.4% and 81.7% individuals who identify as Hispanic or Latino, respectively. 

Given that the community areas of Chicago that have seen an increase in population tend to be more White and have a higher per capita income, it would not be a surprise to see that the city is both more White and has a higher per capita income in the 2020 US Census. The areas that have seen a decrease in population are predominately Black or African American indicating that the relative Black or African American population of Chicago will also decrease in the next census. Additionally, there may be an uptick in the relative population of Hispanics or Latinos as many areas with a large proportion of Hispanics or Latinos saw modest increases in their populations.

The code used for this analysis can be found here.