Posted on May 6, 2015

The Most Diverse Cities Are Often the Most Segregated

Nate Silver, Five Thirty Eight, May 1, 2015

When I was a freshman at the University of Chicago in 1996, I heard the same thing again and again: Do not leave the boundaries of Hyde Park. Do not go north of 47th Street. Do not go south of 61st Street. Do not go west of Cottage Grove Avenue.


On Dustin Cable’s interactive “Dot Map” of racial residency patterns, Hyde Park appears as an island of blue and red dots–meaning, mostly white and Asian students and residents–in contrast to Chicago’s almost uniformly black South Side, designated in green dots. Washington Park, the neighborhood just to Hyde Park’s west, is 97 percent black. Woodlawn–the neighborhood on the other side of 60th Street–is 87 percent black.

Chicago deserves its reputation as a segregated city. But it is also an extremely diverse city. And the difference between those terms–which are often misused and misunderstood–says a lot about how millions of American city dwellers live. It is all too common to live in a city with a wide variety of ethnic and racial groups–including Chicago, New York, and Baltimore–and yet remain isolated from those groups in a racially homogenous neighborhood.


So let’s aim to develop a slightly richer vocabulary. I’m going to describe three statistical measures of segregation and diversity. {snip}


In order to provoke a few questions, I’m going to list the top 10 and bottom 10 U.S. cities by each of the these measures (out of the 100 most populous cities). Chicago, for example, ranks near the top of the charts by one metric, but is at the very bottom on another.

The first measure is the citywide diversity index. It’s defined as the answer to this question: For an average resident in the city, what percent of the people belong to a different racial group?

The lowest possible citywide diversity index is 0 percent, which is what you get if everyone is the same race. The highest possible one is 80 percent. Why not 100 percent? Because the Brown data only includes five racial groups. Even if the population is divided exactly evenly between these groups, you’ll still have 20 percent of the people belong to the same race as you.

{snip} Oakland, California, is not far from being evenly divided between whites, blacks, Hispanics and Asians; its citywide diversity index is 75 percent. New York’s is 73 percent. And Chicago’s is 70 percent.

At the low end of the scale are extremely white cities like Lincoln and Scottsdale, Arizona. There’s also extremely black cities like Detroit, and extremely Hispanic cities like Laredo, Texas. Laredo, which is almost entirely Hispanic, has a citywide diversity index of just 8 percent.


The counterpart to the citywide diversity index is the neighborhood diversity index. It answers basically the same question we asked above, but applied at the neighborhood level. That is: For an average resident in the city, what percent of the people in her neighborhood belong to a different racial group? {snip}

The neighborhood diversity index is always equal to or lower than the citywide diversity index. In other words, if a city doesn’t have much diversity overall, it can’t have racially diverse neighborhoods.

But the reverse can be true, and often is: You can have a diverse city, but not diverse neighborhoods. Whereas Chicago’s citywide diversity index is 70 percent, seventh best out of the 100 most populous U.S. cities, its neighborhood diversity index is just 36 percent, which ranks 82nd. New York also has a big gap. Its citywide diversity index is 73 percent, fourth highest in the country, but its neighborhood diversity index is 47 percent, which ranks 49th.

To be clear, New York and Chicago are still more diverse than cities like Lincoln, even at the neighborhood level. But as the numbers show, they are segregated because they underachieve their potential to have racially diverse neighborhoods.

This is what the final metric, the integration-segregation index, gets at. It’s defined by the relationship between citywide and neighborhood diversity scores. If we graph the 100 most populous cities on a scatterplot, they look like this:


This chart is key to understanding our approach, so let’s take a quick tour, starting in the top-right corner of the chart and moving counterclockwise.

  • The top-right quadrant contains cities like Sacramento, California, that have high neighborhood and citywide diversity scores. They’re both diverse and integrated.
  • The top-left quadrant is empty. In theory, you’d place cities here if they had high neighborhood diversity but poor citywide diversity. But as we’ve said, you can’t have diverse neighborhoods if there’s no diversity in the overall population.
  • In the bottom-left quadrant are cities like Laredo and Lincoln that score poorly on both neighborhood and citywide diversity. Because they’re so racially uniform, you can’t really define them as being either segregated or integrated.
  • The bottom-right quadrant contains highly segregated cities like Chicago, Baltimore and St. Louis. They have average-to-good citywide diversity, but poor neighborhood diversity.
  • The largest group of cities, including those like Los Angeles, are clustered just above these in the middle-right portion of the chart. They’re near the red regression line that indicates the typical relationship between citywide diversity and neighborhood diversity. These cities are reasonably diverse, but a very long way from being perfectly integrated. However, they’re not quite as segregated as cities like Chicago.

The integration-segregation index is determined by how far above or below a city is from the regression line. Cities below the line are especially segregated.