Democrats barely gained in red Iowa. Republicans stayed home almost everywhere else.

Iowa's Democratic share of primary ballots rose from 44% to 47%, mostly because 2022 Republican primary voters stayed home. Gains were smallest in the reddest precincts.

R → D crossover1.9%

of Republican-history voters voted in the Democratic primary

5,703 voters · 3.0% of D ballots

D → R crossover2.1%

of Democratic-history voters voted in the Republican primary

5,789 voters · 2.7% of R ballots

First-time Democrats7.8%

of expected voters with no primary history voted in the Democratic primary

47,514 voters · 24.7% of D ballots

First-time Republicans7.5%

of the same group voted in the Republican primary

45,517 voters · 21.3% of R ballots

Crossover voters followed their neighbors

Crossover rate by precinct 2024 Harris share.

Crossover ran toward the local majority: R → D in Harris country, D → R in the rural west.

R → D peaks in Harris country

0.5% in the most Trump-leaning precincts, 4.6% in Harris's strongest. Among counties with sizable Republican bases, highest in Cherokee, Johnson and Pottawattamie.

D → R is a red-county story

Over 14% in the reddest precincts, under 1% in Harris's strongest. In Sioux County, Randy Feenstra's home in the governor's race, 35% of Democratic-history voters took a Republican ballot.

Partisanship, education and density

Partisanship and density sort the crossovers; education sorts who stayed home.

Dots: random sample of precincts. Lines: LOESS across all precincts, weighted by base size, with 95% bands; dashed lines are statewide rates. Existing-voter turnout: returning past primary voters minus 2022 voters who skipped 2026, as a share of the party's 2022 primary vote.

The primary, precinct by precinct

D → R peaked in Sioux County, Feenstra's home; R → D was highest around Iowa City and the Missouri River.

Pinch or Ctrl/⌘-scroll to zoom, drag to pan, tap a precinct for its value. Download PNG saves the current view.

Who crossed

Point gain: group rate minus statewide rate. Shown only where the gap exceeds sampling error. Groups overlap and don't control for one another.

What moved the margin

The primary margin narrowed by 16,749 votes. Switching was 5%; most came from Republicans who sat out 2026.

5%Switching

83%Existing-voter turnout

12%New voters

	Democratic primary	Republican primary	Margin
2022 primary (reported turnout)	156,589	195,355	R+38,766
Switching	+5,129	+4,247	D+882
Voted the other party's primary in 2022	+3,339	+3,113	D+226
Skipped 2022, last primary was the other party's	+4,903	+4,473	D+430
Voted this party's primary in 2022, the other in 2026	−3,113	−3,339	D+226
Existing-voter turnout	−17,069	−30,939	D+13,870
Skipped 2022 while registered, voted in 2024	+6,387	+19,082	R+12,695
Voted in 2024, registered after the 2022 primary	+717	+1,139	R+422
Skipped 2022, last voted before 2022	+38,128	+35,768	D+2,360
Voted in 2022, skipped 2026	−47,661	−71,827	D+24,166
Voted in 2022, no longer on the voter file	−14,640	−15,101	D+461
New voters	+47,514	+45,517	D+1,997
First primary ever, registered by the 2022 primary	+33,982	+35,963	R+1,981
First primary ever, registered after the 2022 primary	+13,532	+9,554	D+3,978
2026 primary	192,163	214,180	R+22,017
Change	+35,574	+18,825	D+16,749

Democrats grew on new voters

First-time voters added 47,514, more than the entire 35,574-vote Democratic gain. Existing-voter turnout ran 17,069 behind 2022.

Republicans lost more of their 2022 voters

37% of 2022 Republican primary voters skipped 2026, against 30% of Democrats. Returning and first-time voters still grew the Republican primary by 18,825.

2022: Secretary of State reported turnout; 2026: voter file. Skipped 2022 = registered by the June 7, 2022 primary (Iowa has election-day registration). New = no primary ballot 2002–2025.