Polymarket
KalshiIllinois's 11th District: Two Comfortable Foster Wins Leave Walter With Little Room on the Board
The Illinois 11th District odds 2026 board treats Bill Foster's seat in the western and northwestern suburbs as safe, and the market rests on two consecutive Foster wins of more than 34,000 votes rather than on anything new in the 2026 campaign. Foster, a Democrat, faces Jeff Walter, the Republican village president of Elburn, on November 3, 2026, in a district that takes in parts of seven counties from McHenry and Lake down through Kane, DuPage, DeKalb, Will and Boone. The live board above carries Kalshi's and Polymarket's current prices for each party.
Who Is on the Illinois 11th District Ballot
The State Board of Elections' list for the general election, as of October 16, 2026, has two candidates for the 11th: Bill Foster for the Democrats and Jeff Walter for the Republicans. No third-party or independent candidate is listed.
Foster is the incumbent. The Clerk of the House member list, published October 1, 2026, records him as the Democratic member for the 11th, with Naperville as his home town. Shaw Local describes him as a former Fermilab physicist who has represented the 11th since 2013 after an earlier two-year stint in Congress. He was unopposed in the March 17, 2026 Democratic primary and received 69,637 votes.
Walter came out of a four-way Republican primary on March 17, 2026 with 13,877 votes, 42.59% of the party's total. Michael Pierce took 12,653, Charlie Kim 4,197 and Tedora Brown 1,856, which means a majority of Republican primary voters backed someone else and Walter's margin over Pierce was 1,224 votes. Shaw Local describes Walter as the 65-year-old village president of Elburn and a retired IT consultant who served as a village trustee before that, and quotes him naming affordability, tax relief for middle-class voters, utility bills and housing costs as his priorities.
The primary electorates were lopsided in the same direction as the general-election record. Foster's unopposed 69,637 votes were more than twice the 32,583 votes cast across all four Republican candidates. Walter's own 13,877 votes, the most any Republican drew in the district that day, came to about a fifth of Foster's total.
Why the Illinois 11th District Price Treats Foster as Safe
What the price is saying is that the 11th has stopped behaving like a competitive suburban district for a long-serving incumbent, and that a new Republican nominee is unlikely to change that in one cycle. The State Board of Elections' 2022 totals show Foster at 149,172 votes to 115,069 for Republican Catalina Lauf, a margin of 34,103 in a midterm year. The Clerk of the House's statistics for the November 5, 2024 election show Foster at 199,825 to 159,630 for Republican Jerry Evans, a margin of 40,195 out of 359,684 cast.
Those two results are what make this price different from the 8th District's. Here the Democrat is an incumbent with his own record of wins in this electorate, and the margin grew from the midterm to the presidential year. A Republican needs to move roughly twenty thousand of Foster's 2024 voters, or produce a much smaller Democratic turnout, and neither has a public sign behind it.
On October 16, 2026, Polymarket had the Democratic contract at 96%, the cheapest Yes on that side, against Kalshi's 98%, and Polymarket's 2% was the cheapest Republican Yes, against Kalshi's 4%. That means the venues see the 11th as a Democratic hold with only a sliver of doubt. Kalshi's Democratic price sits two points above Polymarket's, a gap that shows how thinly a long-shot board like this one trades on each venue.
The board had about $47K in lifetime volume on Polymarket as of October 16, 2026, more than Polymarket's 8th, 17th or 2nd District boards, and about $27K of that was on the Republican contract; Kalshi had matched about 1,200 contracts, nearly all of them on the Republican side. As on other lopsided boards, the underdog side has drawn more money than the favorite, which is consistent with traders taking small positions on the long shot rather than a market that has moved toward Walter.
The Case Against the Illinois 11th District Read
The strongest case against the read is that the 11th is a suburban district whose margins have been comfortable but not overwhelming, and a midterm can reshape suburban turnout quickly. Foster won the 2022 race by about thirteen points, not thirty, and a swing of six or seven points would have made it even. A reader who holds the counterread would say the price treats a district that has been competitive in the past as if it never could be again.
Walter's profile is part of that argument. A sitting village president from inside the district, running on affordability and taxes, is a local officeholder rather than a repeat nominee, and the 2022 and 2024 Republicans were different candidates. And Foster has held the seat since 2013, which a challenger can turn into a question about whether it is time for someone new.
The price's answer is that this case could have been made in 2022 and 2024 and both times the margin was more than 34,000 votes. The counterread needs evidence of a race closer than either of those, such as an independent poll, before it can carry the price.
What Changes the Illinois 11th District Read
The read would be wrong if the 11th turns out to be closer in a 2026 midterm than its last two results suggest. The dated conditions:
• Public polling: An independent survey of Foster and Walter before November 3, 2026 showing a single-digit race would be the first evidence against the price.
• Campaign money: Federal Election Commission reports filed before the election show how much each campaign has raised and has left to spend.
• Early voting: Early voting at permanent polling places in the district's seven counties begins October 19, 2026, and online registration closes the day before.
• Mail ballots: Applications by mail must reach election authorities by October 29, 2026; ballots postmarked by November 3 and received within 14 days are counted by November 17.
• Certification: County canvasses close by November 24 and the State Board of Elections proclaims the results by December 4, 2026.
When the Illinois 11th District Market Resolves
Kalshi trades this race as its KXHOUSERACE-IL11-26 contracts. The Democratic contract resolves Yes if the member sworn in for IL-11 for the term beginning in 2027 belongs to the Democratic Party, the Republican contract on the same test, and Kalshi lists January 4, 2027 as the expected settlement while allowing an earlier determination once a consensus of media organizations projects the result. Polymarket resolves on the winning candidate's party as a consensus of credible reporting indicates it, and on the Federal Election Commission's official results if there is ambiguity. A candidate's party is the ballot-listed affiliation on Polymarket, so the two-candidate ballot leaves no question about which contract a winner settles.
Related Illinois Markets
The 11th shares the ballot with the statewide races on the Illinois governor odds and Illinois Senate odds pages. The open Illinois 8th District odds board, carries the tightest House price in the state. The other district pages are the Illinois 17th District odds, the Illinois 4th District odds and the Illinois 2nd District odds, and the Illinois elections page lists the whole ballot.
