Illinois had redistricted before this election, and had lost one seat due to reapportionment following the 1950 United States census.

All of Illinois' remaining 26 seats in the United States House of Representatives were up for election in 1942.

W. D. Forsyth defeated former Illinois Treasurer and Auditor of Public Accounts Edward J. Barrett and two other candidates.

John A. Wieland Democratic Vernon L. Nickell Republican Incumbent second-term Superintendent of Public Instruction John A. Wieland, a Democrat, lost re-election, being unseated by Republican Vernon L. Nickell.- Seats in the Illinois Senate were up for election in 1942.

[2] Kenney E. Williamson, one of the Democratic Party nominees, had briefly served before, having been appointed in 1940.

Incumbent Democrat Elwyn Riley Shaw was unseated by Republican William J. Fulton.

An election was held November 3, 1942 to fill two vacancies on the Superior Court of Cook County.