Here’s one way to do it: “diversity density.”
This is a new measure (OK, I invented it) that tries to gauge the real experience of diversity in a city by looking at two things at once. First, is there a wide range of ethnic and racial groups in your city — as opposed to a binary division between white and black, or native and immigrant? And second, is your city’s density high enough so that you really encounter people from different ethnic backgrounds on sidewalks and other shared space, as opposed to simply driving past their neighborhoods on your way to the mall?
The diversity density index measures both at once. And if you use data from the most recent census, you see something surprising: Boston is the third-most diverse city in America, outside of New York and San Francisco.
Diversity density counts the number of people per square mile who do not claim membership in either of the county’s two largest racial/ethnic groups. The result gives you a rough approximation of the likelihood of running into people of a variety of different ethnic backgrounds during a brisk walk across town.
Suffolk County, most of whose residents are in Boston, has 12,338 people per square mile, making it the seventh-most crowded county in the United States. Take away its two largest ethnic groups (non-Hispanic whites and Hispanics), and there remain 3,957 people in other categories per square mile — the sixth highest concentration of all US counties and county equivalents. (Of the five leaders, four are boroughs in New York City.)
This may be surprising to those who remember the Boston of 50 years ago, an overwhelmingly white city with a reputation for racist attitudes that only got worse with the introduction of school busing. Since then, the Hub has lost a sizable number of white residents and has attracted a large immigrant population that is unusually varied in terms of race, language, and educational levels.
