List of United States Senators from Illinois

Illinois was admitted to the Union on December 3, 1818, and has been represented in the United States Senate by 47 senators. Senators from Illinois are elected to Class 2 and Class 3.

The Senate twice refused to seat Frank L. Smith, in December 1926 for an appointed term and in March 1927 for an elected one, due to corruption, but he is included in this list because Smith and the Governor considered him to be a senator for approximately two years.

Of the seven African Americans ever to sit in the U.S. Senate since Reconstruction, three have held Illinois's Class 3 seat.

Class 2

Class 2 U.S. Senators belong to the electoral cycle that were elected for three U.S. Congresses in the first elections of 1818, and then the seat was contested every three Congresses (six years) thereafter. The seat in recent years have been contested in 1996, 2002, 2008, and 2014. The next election will be in 2020.

Class 3

Class 3 U.S. Senators belong to the electoral cycle that were elected for one United States Congress in the first elections of 1818, and then the seat was contested every three Congresses (six years) thereafter. The seat in recent years have been contested in 1998, 2004, 2010, and 2016. The next election will be in 2022.

...
Wikipedia