U.S. House seat · lines in effect since 2022
Illinois's 15th District
A district of about 757,000 people, 26% of adults with a bachelor's degree. It votes R+40.3 relative to the nation for president.
Source: 2026 results: civicAPI; boundaries: Census Bureau TIGER/LineUpdated Nov 7, 2026, 3:01 PM ET
Where it sits among all 435 seats
Every U.S. House seat by partisan lean, from most Democratic to most Republican. Lean is the seat's presidential vote on current lines, relative to the nation.
Democratic
Labels below the bar mark 16 other seats in Illinois.
Source: 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Every race on these lines
Results recomputed from precinct returns as if today's boundaries had always existed, so years compare like for like.
| 2016 | 2018 | 2020 | 2022 | 2026 | |
|---|---|---|---|---|---|
| U.S. Senate | R+24.4 | No race | R+31.2 | No race | No race |
| Governor | No race | R+24.9 | No race | No race | No race |
| U.S. House | No race | No race | No race | R+42.3 | R+33.8 |
Outlined: the race for this seat itselfBlank: no race that year
Source: 99chambers results archive: precinct results allocated to current lines; 2026: civicAPIUpdated Nov 7, 2026, 3:01 PM ET
Who lives here, compared
Grey bars show the spread of all 435 seats. Small marks are other seats in Illinois. The black marker is IL-15.
Lower than 79% of seats.
Higher than 96% of seats.
Lower than 96% of seats.
Lower than 79% of seats.
Lower than 93% of seats.
Less dense than 90% of seats.
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current linesUpdated Oct 13, 2026, 5:06 AM ET
Seats most like this one
Nearest seats on demographics, density and lean.
MO-627% college gradsR+39.0Held RMO-4
25% college gradsR+42.3Held RPA-15
25% college gradsR+38.1Held RIL-12
24% college gradsR+43.9Held R
Source: Census Bureau, American Community Survey 2020–2024 5-year estimates, allocated to current lines; 99chambers: 2024 and 2020 presidential results on current lines, relative to the nation (2024 weighted 3:1)Updated Oct 16, 2026, 5:19 AM ET
Who has held it
These lines took effect in 2022.
- Mary E. Miller (R)
2023– · Won 2022 by 42.3, 2024 by 94.4, 2026 by 33.8
Source: Past results: 99chambers results archive (MEDSL, Klarner, state election offices)