Illinois is the more diverse of the two states. On the U.S. Census Bureau’s 2020 diversity index, Illinois scored close to the national figure of about 61 percent, while Pennsylvania came in well below it, under 50. Both states have a big, diverse metro area (Chicago and Philadelphia), but Illinois has a larger Hispanic and Asian population, and Pennsylvania has a much bigger share of rural, mostly non-Hispanic White counties.
Below is a practical breakdown of what the diversity index measures, how the two states compare, where the diversity is concentrated, and how to keep up with the local stories behind the numbers.
How the diversity index works
The Diversity Index (DI) is the Census Bureau’s shorthand for a probability: the chance that two people picked at random from an area belong to different racial or ethnic groups. It runs from 0 (everyone is in the same group) to 100 (every pair is different), and it is often shown as a percentage.
The groups come from the census race and Hispanic origin questions: Hispanic or Latino, plus non-Hispanic White, Black, Asian, American Indian and Alaska Native, Native Hawaiian and Other Pacific Islander, some other race, and people who report two or more races.
Keep three limits in mind when you compare states:
- A state with two large, roughly equal groups can score higher than a state with one very large group and several tiny ones.
- The index does not capture income, religion, language, national origin within a group, or immigration status.
- Coding changes in the 2020 Census counted more people as multiracial, so part of the rise from 2010 to 2020 is methodological.
Pennsylvania vs Illinois at a glance
These are rounded, approximate figures drawn from recent Census Bureau data. They are meant for comparison, not as exact counts.
| Measure | Pennsylvania | Illinois |
|---|---|---|
| Population | About 13 million | About 12.5 to 12.8 million |
| 2020 diversity index | Below 50 | Around 60 |
| Non-Hispanic White share | Roughly three quarters | Roughly 60 percent or a bit less |
| Hispanic or Latino share | Around 8 to 9 percent | Around 18 to 19 percent |
| Black share | Around 10 to 11 percent | Around 14 percent |
| Asian share | About 4 percent | About 6 percent |
| Main diversity hub | Philadelphia and its suburbs | Chicago and Cook County |
The gap is mostly explained by Hispanic population size. Illinois has more than twice Pennsylvania’s Hispanic share, largely because Chicago has been one of the main destinations for Mexican immigrants for over a century.
Where Pennsylvania’s diversity lives
Pennsylvania is a state of contrasts. Its two biggest cities sit at opposite ends, with a huge stretch of small towns, farmland and forest in between.
Philadelphia
Philadelphia is by far the most diverse part of the state. The city is roughly 40 percent Black, with sizable Hispanic (especially Puerto Rican) and Asian communities. Neighborhoods like North Philadelphia’s Fairhill, South Philadelphia’s Italian Market area (now home to large Mexican and Southeast Asian communities as well), Chinatown and the Northeast’s Russian and Ukrainian enclaves show how the city layers old and new immigration.
The Lehigh Valley and eastern cities
Some of the fastest demographic change in Pennsylvania has happened in smaller cities. Reading and Allentown are majority Hispanic, and Hazleton in Luzerne County went from overwhelmingly White to majority Hispanic within about two decades, driven largely by Dominican families moving from New York and New Jersey for jobs and lower housing costs.
Pittsburgh and the west
Pittsburgh is less diverse than Philadelphia, though it has a long-established Black community and growing international populations tied to its universities and hospitals, including Bhutanese Nepali refugees in the South Hills. Much of western and central Pennsylvania remains overwhelmingly non-Hispanic White, which pulls the statewide score down. Lancaster County adds a different kind of cultural distinctiveness through its Amish and Mennonite communities, which the census counts as White but which maintain their own language and traditions.
Where Illinois’s diversity lives
Illinois is often described as Chicago plus “downstate,” and the diversity index follows that split closely.
Chicago, the city of neighborhoods
Chicago is divided almost evenly among non-Hispanic White, Black and Hispanic residents, each at roughly 30 percent, with Asian residents making up most of the rest. That balance produces a very high diversity score at the city level. The catch is that Chicago is also one of the most residentially segregated big cities in the country, so a neighborhood can be almost entirely one group even when the city as a whole is highly mixed.
Well-known community anchors include Pilsen and Little Village (Mexican American), Humboldt Park (Puerto Rican), Bronzeville (historic center of Black Chicago), Devon Avenue (South Asian), Chinatown and Argyle Street (Chinese and Vietnamese), and the Northwest Side’s long Polish presence.
The suburbs
Chicago’s suburbs are increasingly diverse. Cicero and Berwyn have large Hispanic majorities or pluralities, Skokie and the northwest suburbs have large Asian and immigrant populations, and Aurora and Elgin have fast-growing Hispanic communities. In many suburban school districts, students now speak dozens of home languages.
Downstate Illinois
Outside the Chicago area, most counties are far less diverse. There are notable exceptions: East St. Louis is majority Black, college towns like Champaign-Urbana draw international students, and meatpacking and manufacturing towns such as Beardstown and Rockford have attracted immigrant workers.
What the numbers mean for residents
Diversity scores become useful when you connect them to decisions people actually make:
- Schools: Districts with many home languages need more English learner teachers and translated materials. That is a bigger issue in suburban Cook, DuPage and Kane counties than in most of rural Pennsylvania, though Reading and Allentown face similar needs.
- Healthcare: Hospitals in Philadelphia and Chicago routinely provide interpreters in Spanish, Chinese, Arabic, Polish and many other languages.
- Business: Employers recruiting in Chicago or Philadelphia draw from a far more varied labor pool than in rural counties, which affects hiring, marketing and customer service.
- Policy: State and local agencies use census and survey data to decide where to focus language access, small business support and community outreach.
Keeping up with state news and data
Census releases are only a snapshot. To follow what is happening between them, local news and press platforms are a practical source for community events, business announcements, nonprofit programs and local government updates. Pennsylvania PR News covers news and releases from across Pennsylvania, from Philadelphia and Pittsburgh to smaller cities and rural regions, which helps you see how change is playing out in places the statewide averages hide.
For Illinois, Illinios PR Market publishes state news and announcements, useful for tracking what organizations, businesses and communities in Chicago and beyond are doing.
A few habits make any diversity story easier to evaluate:
- Note whether a number comes from the decennial census or the American Community Survey (ACS), which is an estimate with a margin of error.
- Look at county, city or even census tract figures rather than a single statewide average.
- Be cautious with year-over-year comparisons that span 2010 and 2020, because of the coding changes described above.
How the two states are changing
Both states grew slowly in the 2010s, and both have relied on immigration and Hispanic and Asian population growth to offset declining numbers of non-Hispanic White residents. Illinois lost population in the late 2010s and early 2020s, with many residents moving to other states, while Pennsylvania roughly held steady.
Over the next decade, Pennsylvania’s score is likely to keep rising as eastern cities and the Philadelphia suburbs diversify. Illinois is already near the national average, so its future score depends heavily on whether Chicago keeps attracting new immigrants. The federal government’s 2024 update to race and ethnicity standards, which combines the race and Hispanic origin questions and adds a Middle Eastern or North African category, will also change how future scores are calculated.
For more side-by-side comparisons, see our breakdowns of Florida vs New York and Ohio vs Georgia, or browse the Daily Bites category.
Frequently asked questions
Is Illinois more diverse than Pennsylvania?
Yes. Illinois scored around 60 on the Census Bureau’s 2020 diversity index, close to the national average, while Pennsylvania scored below 50. The biggest reason is Illinois’s much larger Hispanic population.
What is the most diverse city in Pennsylvania?
Philadelphia is the most diverse large city. Smaller cities such as Allentown, Reading and Hazleton have also become highly diverse because of rapid Hispanic population growth.
Why is Chicago so diverse?
Chicago has drawn immigrants for more than 150 years, from Germany, Ireland and Poland to Mexico, Puerto Rico, India, China and many other places, and it was a major destination during the Great Migration of Black Americans from the South.
Does a high diversity index mean a city is integrated?
Not necessarily. The index measures the mix across a whole area. A city can score high overall while individual neighborhoods remain largely made up of one group, which is the case in parts of Chicago and Philadelphia.
Where can I find exact diversity index figures?
The Census Bureau publishes diversity index figures for states and counties from the 2020 Census through its data visualizations and the data.census.gov platform.
