Wednesday, January 14, 2015

A City Can Be Diverse, but its Neighborhoods Might Not Be. DC Scores Poorly on Both Measures

The diversity of each census tract in DC.

How do you measure a city's diversity? If a city has a lot of different racial and ethnic groups in their own segregated sections, is that diverse? A blog called priceonomics recently ranked major American cities on diversity by looking at the percentage of major racial and ethnic groups within the city's limits. The District of Columbia came in 21st, slightly less diverse than Oklahoma City. 

However, while this analysis is useful, it it doesn't reveal whether the neighborhoods in each city are themselves diverse, or whether the city boundary just encompasses some all-black areas, other all-white areas, and so on.

If we modify this methodology to measure the average diversity of a city's neighborhoods, rather than of the city as a whole, we are able to quantify how integrated these place are. On this new measure, the District performs even worse.

A Neighborhood-Level Calculation Changes the Results

Consider Chicago. With roughly equal-sized black, white, and Latino populations, the Windy City ranks as the fifth most diverse city in the country on the priceonomics scale. However, if we instead use priceonomics' same methodology (it took the percentage of black, white, Asian, Latino, and other people in the city, then used a Herfindahl-Hirschman Index to combine those numbers into a single score) for each of Chicago's individual census tracts, then take the weighted average, Chicago suddenly drops to 38th out of 45.

(Click a city's name to view its map)
NameNew RankDiversity Index
Original RankDiversity Index
Rank Change
Long Beach30.40482440.2853671
San Jose50.41991260.2959631
San Francisco60.42005080.3118102
Las Vegas70.439887170.33810610
San Diego80.46835190.3127091
Fort Worth90.478435130.3246714
Oklahoma City140.502493200.3743756
Virginia Beach150.510308330.45543618
New York190.52082730.260531-16
Los Angeles210.526386180.339228-3
Colorado Springs300.565902410.52823311
San Antonio320.574919350.4746363
Kansas City330.579408280.399368-5
El Paso430.706141440.6633451
Note: Priceonomics used the 2013 1-year American Community Survey estimates for their analysis. This analysis uses the 5-year estimates, because it is available at both the Place and Census Tract levels. As a result, the citywide index scores may vary slightly from the data presented by Priceonomics.

Chicago, as a whole, is diverse, but its neighborhoods are not. The average Chicago census tract is less diverse than a typical tract in Portland or Colorado Springs, both relatively homogeneous cities that scored near the bottom in the original citywide index. Both are close to 70% white, but the non-white population isn't all clumped in a small non-white area.

Chicago's diverse population is largely segregated. Sacramento is diverse, and so are its neighborhoods.

California cities dominate the adjusted rankings, accounting for the top six spots: Sacramento, Oakland, Long Beach, Fresno, San Jose, and San Francisco. Virginia Beach moved up 18 slots, representing the largest jump of any one city.

DC, on the other hand, drops into the bottom quartile, neck and neck with Omaha. Like Chicago (well, not quite as bad as Chicago), the District's citywide diversity doesn't extend to diversity within most of its neighborhoods.

How Citywide Diversity Relates to Neighborhood Diversity

There is a correlation between diversity in a city and diversity within its neighborhoods, although places like Chicago and DC remind us that it is not necessarily as strong relationship. Here's a scatter plot comparing the citywide and neighborhood average diversity indices for each of the 45 cities:

Diversity within neighborhoods compared to overall city diversity, with the most integrated and most segregated cities labeled.

Cities above the trend line have less diverse census tracts than the city's overall diversity would suggest. These are therefore relatively segregated. Chicago and DC fall into this category.

Miami is among the least diverse cities on the entire list (remember that according to this methodology, "diversity" only considers 5 distinct groups, lumping together, for example, everyone who identifies as Hispanic/Latino), but on a neighborhood level it's even more segregated still.

Cities below the trend line have neighborhoods that are more diverse than comparable cities at their level of citywide diversity. This group includes Sacramento, which is both diverse and integrated, as well as Portland, which is not diverse, but relatively well-integrated.

Diversity and integration are both important, and the District has a long way to go on both measures.

Cross-posted at Greater Greater Washington