2024Final results
2024 election for Iowa Senate District 8
Iowa State Senate · Iowa
Mark Costello (R) won with 70.5% of the vote, defeating Ryan Lee Roenfeld (D) by 41.1 points.
Mark CostelloRepublican · winner
70.5%25,069
Ryan Lee RoenfeldDemocrat
29.3%10,432
The same year, the district voted R+37.8 for president; this race was R+41.1.35,574 votes
Source: MIT Election Data and Science LabUpdated Sep 30, 2026, 12:13 PM ET
The seat over time
D − R margin in this seat's races around 2024
Races before and after
Source: MIT Election Data and Science LabUpdated Sep 30, 2026, 12:13 PM ET