Illinois District 12

22 Compact

Less compact than 16% of other congressional districts.

362nd least compact of 429 nationally, 17th of 17 in Illinois.

A score describes shape, not intent. Coastlines, rivers and the Voting Rights Act can all make a district irregular. How scores work

The three measures

Polsby-Popper: 0.27at least as compact as 56% of districts on this measure
Area compared with perimeter. Low for jagged or snaking edges.
Reock: 0.71at least as compact as 92% of districts on this measure
Area compared with the smallest circle around the district, counting only land. Low for stretched shapes.
Convex hull: 0.89at least as compact as 87% of districts on this measure
Area compared with a rubber band stretched around the district, counting only land. Low for bites and tentacles.

Each measure runs from 0 to 1, where 1 is a perfect circle or a shape with no dents.

The state's edge

65% of this district's border is the state's edge: a coastline, a national border or a state line. Mapmakers don't choose those lines. A ragged one, like a coastline or a river, lowers Polsby-Popper. Reock and convex hull count only the state's own land, so water and neighboring states don't count against them. More on the state's edge

Cities and towns

The largest places with people in this district, from the 2020 Census. A place split between districts shows how many of its residents live in this one.

O'Fallon city22,337 of its 32,289 residents
Carbondale cityall 21,857 residents
Marion cityall 16,855 residents
Mount Vernon cityall 14,600 residents
Herrin cityall 12,352 residents
Effingham cityall 12,252 residents
Centralia cityall 12,182 residents
Waterloo cityall 11,013 residents
Columbia cityall 10,999 residents
Mascoutah cityall 8,754 residents

And 272 smaller places. 39% of this district's people live outside any city, town or named community. How places are counted

2024 presidential vote

Kamala Harris 28.0%, Donald Trump 72.0%

Shares of the votes for the two of them; other candidates are left out. Illinois used the same lines in 2024, so this is added up from precinct results. A precinct split between districts is divided by its House votes, so the figures are close estimates. Where the votes come from

U.S. House

Statewide results from Illinois for the November 3, 2026 election aren't available yet.

Where this comes from

Illinois's senators

Tammy Duckworth, Democrat
Richard J. Durbin, DemocratSeat on the November 3, 2026 ballot: results aren't available yet.

Senators are elected by the whole state, so district lines don't change who they are. Senators serving as of November 6, 2026. Senators elected in November 2026 take office January 3, 2027. Where this comes from

Where it sits in Illinois

Very compact (0 to 19)
Compact (20 to 39)
Middle (40 to 59)
Irregular (60 to 79)
Very irregular (80 to 100)