Polls close: 8 p.m. ET

Presidential race: Hillary Clinton (D) vs. Donald Trump (R)

Illinois, which has 20 electoral votes, had voted Republican in six consecutive presidential elections before Bill Clinton won it in 1992, and it hasn't flipped back since. Again, the state can claim a connection to the Democratic nominee: Hillary Clinton grew up in Park Ridge, a close-in Chicago suburb.

Rating: Safe D

Senate race: Mark Kirk (R) (i.) vs. Tammy Duckworth (D)

Kirk was always likely to lose to Duckworth, but a series of gaffes -- including the latest dig at Duckworth's heritage -- made overcoming the state's Democratic tilt nearly impossible.

Rating: Likely D

House races to watch

IL-10 (Northern Chicagoland): Robert Dold (R) (i.) vs. Brad Schneider (D)

It's a rubber match between Schneider (who beat Dold in 2012) and Dold (who beat Schneider two years later). The district gave 58% of the vote to Obama in 2012, while Dold won it by 2 points in 2014.

Rating: Toss up

IL-12 (Southwest Illinois): Mike Bost (R) (i.) vs. C.J. Barijevic (D)

Bost unseated an incumbent two years ago by 10 points. It's a swing district dominated by blue-collar voters, and Trump is less of an albatross here than in Dold's North Shore district, for example.

Rating: Likely R