Trends in Racial and Ethnic Diversity

The racial and ethnic diversity of the U.S. population has increased dramatically in recent decades. Immigration from Latin America and Asia is a key driver of this trend, in part because the newly arrived immigrant groups tend to have youthful age structures and higher fertility. Intermarriage (and the resulting multiracial offspring) and shifts in racial-ethnic identity also play significant roles in boosting diversity.

Although the national trend is clear, diversity levels differ markedly across communities. In some places the major ethnoracial groups make up similar shares of the population, reflective of greater diversity. But other places remain completely homogeneous, with all residents belonging to the same group. Such variation in diversity can have important implications for the local economy, politics, schools, healthcare, and other social institutions.

Initial evidence on local diversity patterns was presented in a Russell Sage Foundation-sponsored US2010 report by Barrett Lee, John Iceland, and Gregory Sharp. Shortly after that report came out, Lee received a research grant from the National Institutes of Health. The grant enabled him and a team of co-investigators to study community racial-ethnic diversity in greater detail for several types of geographic units. More information about this project and the publications resulting from it can be found here.

Diversity Data

Data files from Lee’s NIH-funded project include total population, group-specific counts and percentages, and an overall diversity index for the census years 1980, 1990, 2000, and 2010. The diversity index (also known as the entropy index) indicates how far a community’s population composition departs from perfect homogeneity (where a single group constitutes the entire population). The most diverse community would be one in which there are equal numbers of people in five ethnoracial categories: (1) non-Hispanic whites, (2) non-Hispanic blacks, (3) non-Hispanic Asians and Pacific Islanders, (4) Hispanics of any race, and (5) a combined ‘other’ category that includes non-Hispanic American Indians and Alaska Natives, other races, and multiracial individuals. For a technical description of the diversity index, click here.

Diversity data are available from this website for five types of geographic units. As defined by the Census Bureau, a metropolitan statistical area consists of one or more principal cities of at least 50,000 residents, the core counties in which the principal cities are located, and any surrounding counties that are integrated with the core counties through strong commuting ties. A micropolitan statistical area is similar to a metropolitan area but smaller, with no principal city reaching a population of 50,000. In the diversity data files, both metropolitan and micropolitan areas have been delimited in terms of their 2010 boundaries for all earlier time points.

Census-defined places comprise cities, suburbs, small towns, boroughs, and villages. The majority of places are incorporated as legal or governmental jurisdictions, but many are not. (The latter are known as CDPs, or census-designated places.) Because place boundaries can change through annexation or loss of territory, the diversity data files include a measure of size (square miles) in each census year that a place existed. We provide 1990 through 2010 diversity data for all places with non-zero populations. In 1980, however, comparable data were only reported by the Census Bureau for places with populations of 1,000 or more.

Finally, diversity data are available for counties and states, more familiar units with generally stable boundaries over time.

Data Access

You can access the diversity data in three ways:

• Use the pull-down menus below. These are most appropriate if you only need data for a small number of specific units. The display shows year-by-year diversity indexes, group counts and percentages, and compositional pie charts.
• Click here for sortable lists, which are useful for ranking purposes. The display includes the name of each unit and its diversity index score for the specified year.
• Click here to download spreadsheet data files. This is the best choice if you plan to incorporate racial-ethnic diversity and composition measures into your own analysis.

NOTE: The diversity data files available at this site were corrected and expanded in September 2017.

Pull-Down Menus

Select a Metropolitan Area: