Iowa
4 congressional districts.
Map
- Very compact (0 to 19)
- Compact (20 to 39)
- Middle (40 to 59)
- Irregular (60 to 79)
- Very irregular (80 to 100)
Select a district for details.
Map used in 2026
2021 enacted plan (SF 621; second LSA plan)
- Drawn by
- the state legislature
- Enacted
- 2021-11-04
- Changed since 2024
- No
Source: All About Redistricting, Loyola Law School (secondary source) (checked 2026-11-04)
Districts
| District | Irregularity | National rank |
|---|---|---|
| IA-01 | Irregularity score 56 Middle of the pack | 174th least compact |
| IA-02 | Irregularity score 18 Very compact | 378th least compact |
| IA-03 | Irregularity score 32 Compact | 312th least compact |
| IA-04 | Irregularity score 35 Compact | 301st least compact |
Scores describe shape, not intent. How scores work
Iowa's senators
- Joni Ernst, RepublicanSeat on the November 3, 2026 ballot: Josh Turek, Democrat, won and takes office January 3, 2027.
- Chuck Grassley, Republican
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
Partisan fairness
How the 2024 presidential vote splits across these districts. Kamala Harris (Democrat) won 43.3% of the two-party vote. Donald Trump (Republican) carried all 4 districts.
When one party carries every district, the efficiency gap is large however the lines are drawn, since every vote for the other party counts as wasted. Declination needs districts won by both parties, so it can't be measured here.
- Efficiency gap
- 36.5% Favors Republicans
Counts each party's wasted votes: votes for a losing candidate, plus a winner's votes beyond the half needed to win. The gap is the difference between the two parties' wasted votes, as a share of all votes.
- Mean-median difference
- 2.2 points Favors Democrats
The gap between a party's average vote share across the districts and its share in the middle (median) district. When the middle district leans away from a party's average, that party's voters are packed into a few lopsided districts.
- Declination
- Not measurable
Compares how lopsided each party's wins are. A party that wins a few districts by huge margins and loses the rest narrowly is at a disadvantage. Runs from 0 (even) to 1.
Votes are 2024 presidential results by precinct, added up within each district. This state used the same districts in 2024 and 2026. These measures show how a map turns one election's votes into seats. They don't show why the lines were drawn, and they shift from one election to the next. How fairness scores work