The district has a Cook Partisan Voting Index score of D +20.[4] The district and its predecessors have been in Democratic hands for all but four years since 1909. Two of those years came after Dan Rostenkowski lost his seat to Republican Michael Patrick Flanagan because of the Congressional Post Office scandal. On a national level, the scandal helped prompt the Republican Revolution of 1994. However, Flanagan was defeated after only one term by State Representative Rod Blagojevich in 1996, and no Republican has managed even 35 percent of the vote in the district since then. Blagojevich handed the seat to Emanuel in 2003.
Following the 2020 redistricting, this district will shift from a Chicago-based district to one primarily based in Cook County with a portion in southern Lake County.
Lake County is split between this district and the 9th district. They are partitioned by the Fox River, Kelsey Rd, W Miller Rd, Echo Lake Rd, Sacomano Meadows Pond 1, Midlothian Rd, N Old Henry Rd, N Quentin Rd, Lake Zurich Rd, Twin Orchard Country Club, Mundelein Rd, Hicks Rd, Bridgewater Farm, Crossing Pond Park, and Arlington Heights Rd. The 5th district takes in the municipalities of Deer Park and Kildeer; the vast majority of Lake Zurich; the southern half of Long Grove; and the portion of North Barrington south of Miller Rd.
This table indicates how the district has voted in U.S. presidential elections; election results reflect voting in the district as it was configured at the time of the election, not as it is configured today.
This table indicates how the district has voted in recent statewide elections; election results reflect voting in the district as it is currently configured, not necessarily as it was at the time of these elections.