2018Flipped from RepublicanFinal results
2018 election for Illinois's 6th District
U.S. House · Illinois
Sean Casten (D) won with 53.5% of the vote, defeating Peter J. Roskam (R) by 7.1 points, a seat Republicans won last time.
Sean CastenDemocrat · winner
53.5%169,001
Peter J. RoskamRepublican
46.4%146,445
315,711 votes
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 6:17 AM ET
The seat over time
D − R margin in this seat's races around 2018
Races before and after
Source: MIT Election Data and Science LabUpdated Oct 1, 2026, 6:17 AM ET
Money in this race
Each line compares the two campaigns on one scale.
Sean CastenPeter J. Roskam
$6.4M
Raised by the campaign
$7.1M
$6.4M
Spent by the campaign
$7.2M
$77.5K
Cash on hand
$20.1K
Campaign money: FEC, through Dec 31, 2018.
Source: FEC campaign filingsUpdated Dec 31, 2018