Redistricting history and process
Since it became a state, Illinois has had as many as 26 congressional districts. By 1900, Illinois had reached an impressive 25 congressional districts and a population ranking behind only New York and Pennsylvania. The state peaked at 27 representatives in 1910. However, the state has lost representation in every Census since 1940; today, Illinois has only 17 congressional districts, its lowest total since the 1860s.
Like the rest of the “Rust Belt”, Illinois faces a declining or stagnating population. Under current forecasts, it’s expected that Illinois will lose two congressional districts as a result of the 2030 Census. Unless population trends reverse, it’s likely that Illinois’s standing will continue to slip in favor of rapidly-growing states in the “Sun Belt”.
Prior to 1992, Illinois had long been a Republican-leaning swing state at the federal level. From 1952 to 1988, Republicans won eight of ten presidential races in the state, including six straight from 1968 on. Since 1992, Illinois has solidified itself as a Democratic stronghold. Alongside California and New York, it is one of the three biggest prizes in the “blue wall”. At the state level, however, Illinois remained more competitive; Republicans won gubernatorial elections in 1994, 1998, and 2014, Senate elections in 1998 and 2010, and a majority of congressional districts in 2002 and 2010.
Modern Illinois politics are sharply divided between the Chicagoland area, which is strongly Democratic, and downstate, which is strongly Republican. Because Chicagoland has far more residents than downstate, the state leans heavily Democratic in federal elections, and most state elections as well.
In Illinois, congressional districts and state legislative districts are drawn by the legislature, subject to gubernatorial veto. Democrats have used this authority to draw harsh gerrymanders in both the 2010s and 2020s that rank among the ugliest in the nation. Democrats won 14 of the state’s 17 districts in 2022, and only two districts (CD13 and CD17 in downstate) could be deemed competitive. The Illinois Supreme Court has twice rejected attempts to place redistricting reform initiatives on the ballot.
Demographic breakdown
| District | White | Hispanic | Black | Asian | Native | Pacific |
| 1 | 37.0% | 7.9% | 52.0% | 2.6% | 1.4% | 0.1% |
| 2 | 36.3% | 13.4% | 48.4% | 1.3% | 1.8% | 0.1% |
| 3 | 42.8% | 43.8% | 6.0% | 7.3% | 3.5% | 0.2% |
| 4 | 26.2% | 63.2% | 5.8% | 4.7% | 4.8% | 0.1% |
| 5 | 73.3% | 10.7% | 3.3% | 11.8% | 1.2% | 0.1% |
| 6 | 74.6% | 11.8% | 5.9% | 6.5% | 1.3% | 0.1% |
| 7 | 32.7% | 13.9% | 43.0% | 10.2% | 1.5% | 0.1% |
| 8 | 58.4% | 20.7% | 4.8% | 15.2% | 2.1% | 0.1% |
| 9 | 61.6% | 11.7% | 9.7% | 16.0% | 1.5% | 0.1% |
| 10 | 61.6% | 21.2% | 7.1% | 8.7% | 2.2% | 0.2% |
| 11 | 66.6% | 16.4% | 6.6% | 9.0% | 1.8% | 0.1% |
| 12 | 88.1% | 2.4% | 5.6% | 1.4% | 2.0% | 0.1% |
| 13 | 67.8% | 4.3% | 20.3% | 5.4% | 2.1% | 0.1% |
| 14 | 62.7% | 20.1% | 10.2% | 5.7% | 2.2% | 0.1% |
| 15 | 90.9% | 2.4% | 3.4% | 1.0% | 1.8% | 0.1% |
| 16 | 87.3% | 5.3% | 2.7% | 2.5% | 1.8% | 0.1% |
| 17 | 72.0% | 9.4% | 14.2% | 2.6% | 2.0% | 0.1% |
| State | 61.2% | 16.2% | 14.7% | 6.6% | 2.1% | 0.1% |
Illinois ranks as above-average nationally in diversity, especially compared to the rest of the midwest. It has the 16th-lowest non-Hispanic White population of any state, the 16th-highest Black population, and the 10th-highest Hispanic population. Diversity in Illinois is generally concentrated around Chicago, the state’s largest city, which has a virtually even proportion of White, Hispanic, and Black residents. Asians are not a particularly prominent group in Illinois, although they do make up over 10% of the electorate in four Chicago-area districts.
Ethnic tensions in Chicago are known to be high. Despite the city’s firm Democratic grip, most primary and citywide elections in Chicago fall firmly along racial lines. This trend, along with persistent inequities in crime, healthcare, and income, have led to the common refrain among mapmakers and political analysts that “every map of Chicago is the same”.
In contrast to Chicago, downstate Illinois is predominantly rural and white. The largest cluster of non-White voters is based around East St. Louis, which has a high proportion of Black voters.
| District | Bachelor’s or higher | Rank (of 435) | Non-college white | Rank (of 435) |
| 1 | 30.3% | 223 | 24.7% | 348 |
| 2 | 23.0% | 357 | 31.4% | 306 |
| 3 | 33.8% | 167 | 26.8% | 341 |
| 4 | 22.2% | 374 | 20.9% | 365 |
| 5 | 62.9% | 7 | 26.9% | 337 |
| 6 | 42.8% | 78 | 44.7% | 206 |
| 7 | 45.0% | 64 | 8.7% | 425 |
| 8 | 37.5% | 119 | 41.4% | 241 |
| 9 | 53.8% | 19 | 28.5% | 329 |
| 10 | 45.4% | 59 | 33.9% | 289 |
| 11 | 43.5% | 75 | 39.5% | 260 |
| 12 | 22.8% | 362 | 69.7% | 25 |
| 13 | 30.0% | 233 | 50.6% | 149 |
| 14 | 31.5% | 199 | 45.5% | 194 |
| 15 | 24.2% | 331 | 70.8% | 18 |
| 16 | 29.2% | 246 | 65.3% | 48 |
| 17 | 23.6% | 340 | 58.3% | 86 |
Illinois has the 13th-largest percentage of residents with bachelor’s degree of any state, and six of its congressional districts rank in the first quartile. However, like in many states, there is a broad inequality in educational attainment. All five districts based in downstate Illinois have low rates of educational attainment, and four of them rank in the top quartile for non-college Whites. Districts in the South Side and West Side of Chicago also have below-average rates, with several ranking in the fourth quartile.
Political history
| District | Biden | Trump | Margin | Shift |
| 1 | 70.5% | 28.1% | D+42.4% | R+5.6% |
| 2 | 69.3% | 29.3% | D+40% | R+2.3% |
| 3 | 69.7% | 28.3% | D+41.4% | R+3% |
| 4 | 72.3% | 25.9% | D+46.4% | R+4.3% |
| 5 | 69.0% | 29.2% | D+39.8% | D+1.6% |
| 6 | 54.5% | 43.6% | D+10.9% | D+2.6% |
| 7 | 85.6% | 12.8% | D+72.8% | R+3.2% |
| 8 | 56.8% | 41.4% | D+15.4% | R+0.2% |
| 9 | 69.8% | 28.5% | D+41.3% | R+1.1% |
| 10 | 62.0% | 36.1% | D+25.9% | D+3.1% |
| 11 | 56.6% | 41.3% | D+15.3% | D+4.7% |
| 12 | 27.7% | 70.5% | R+42.8% | R+0.2% |
| 13 | 54.4% | 43.2% | D+11.2% | D+2.9% |
| 14 | 54.7% | 43.3% | D+11.5% | D+2.9% |
| 15 | 29.6% | 68.3% | R+38.7% | R+0.4% |
| 16 | 38.1% | 59.6% | R+21.5% | D+2.3% |
| 17 | 52.7% | 44.9% | D+7.8% | D+1.2% |
| State | 57.5% | 40.5% | D+17.0% | D+0.1% |
Although Joe Biden carried Illinois by a 17-point margin, this margin was virtually unchanged from 2016 even as the popular vote trended 2.4% to the left. This shift is primarily due to an unusual factor: a relative overperformance from Donald Trump in staunchly Democratic Cook County. This was balanced out, by the Democratic trend of Chicago’s affluent suburbs, as well as a slight reversion among working-class voters in downstate Illinois.
If one were to divide Illinois into three regions – Cook County, the Chicago suburbs, and downstate – they’d find an interesting pattern. In 2020, Trump carried downstate by 18.3% (a 0.9% decline from 2016), while Biden carried Cook County by 50.4% (a 2.7% decline from 2016). In Chicago’s affluent collar counties, however, Joe Biden won by 12.4% – a 3.2% improvement on Hillary Clinton’s margins. These gains have effectively choked off Republican chances in suburban seats which would have been competitive a decade ago.
2022 election results
| District | Incumbent | Democratic | Republican | Result |
| 1 | Jonathan Jackson (D) | 67.0% | 33.0% | D+34% |
| 2 | Robin Kelly (D) | 67.1% | 32.9% | D+34.2% |
| 3 | OPEN | 68.5% | 31.5% | D+37% |
| 4 | Chuy García (D) | 68.4% | 28.1% | D+43.3% |
| 5 | Mike Quigley (D) | 69.6% | 28.8% | D+40.8% |
| 6 | Sean Casten (D) | 54.4% | 45.6% | D+8.8 |
| 7 | Danny Davis (D) | 100.0% | – | – |
| 8 | Raja Krishnamoorthi (D) | 56.9% | 43.1% | D+13.8% |
| 9 | Jan Schakowsky (D) | 71.7% | 28.3% | D+43.4 |
| 10 | Brad Schneider (D) | 63.0% | 37.0% | D+26 |
| 11 | Bill Foster (D) | 56.5% | 43.5% | D+13.5 |
| 12 | Mike Bost (R) | 25.0% | 75.0% | R+50 |
| 13 | OPEN | 56.6% | 43.4% | D+13.2 |
| 14 | Lauren Underwood (D) | 54.2% | 45.8% | D+8.4 |
| 15 | Mary Miller (R) | 71.1% | 28.9% | R+42.2 |
| 16 | Darin LaHood (R) | 66.3% | 33.7% | R+32.6 |
| 17 | OPEN | 52.0% | 48.0% | D+4 |
Under the new Illinois congressional gerrymander, congressional Democrats netted three seats. Democrats only flipped one seat – the 13th district in downstate, a narrow string slicing through a handful of Democratic-leaning cities. Republicans also lost an additional district to redistricting. Democrats were able to hold all competitive districts.
Democratic strength was so durable in Illinois in large part due to the leftward trend of the Chicago suburbs. Much of this area was competitive or Republican-leaning in 2010 and 2014. However, the region realigned under the Trump era and the affluent, college-educated voters that occupy the Chicago suburbs have broadly abandoned the Republican Party.
Current Representatives
- IL-01: Jonathan Jackson (D-Chicago)
- IL-02: Robin Kelly (D-Matteson)
- IL-03: Delia Ramirez (D-Chicago)
- IL-04: Chuy García (D-Chicago)
- IL-05: Mike Quigley (D-Chicago)
- IL-06: Sean Casten (D-Downers Grove)
- IL-07: Danny Davis (D-Chicago)
- IL-08: Raja Krishnamoorthi (D-Schaumburg)
- IL-09: Jan Schakowsky (D-Evanston)
- IL-10: Brad Schneider (D-Highland Park)
- IL-11: Bill Foster (D-Naperville)
- IL-12: Mike Bost (R-Murphysboro)
- IL-13: Nikki Budzinski (D-Springfield)
- IL-14: Lauren Underwood (D-Naperville)
- IL-15: Mary Miller (R-Oakland)
- IL-16: Darin Lahood (R-Peoria)
- IL-17: Eric Sorenson (D-Moline)