University of Illinois Urbana‑Champaign

Geographic Regions: State House and Senate Districts

The legislative power of the state is vested in the General Assembly, which is composed of a 59-member Senate and a 118-member House of Representatives.

Each Senate district is divided into two House districts. Members of the General Assembly are elected in the general election in even-numbered years. Every two years, one representative is elected from each House district for a two-year term. Senate districts are divided into three groups, and one or two groups of senators are elected every two years. Each group has a two-year term at a different part of the decade between censuses, with the rest taken up by two four-year terms.

After each decennial census conducted by the U.S. Census Bureau, the House and Senate districts are redrawn. The new districts are the basis for the next general election, and the new districts take effect in the General Assembly after that election.

Thus, after the 2020 Census, the state House and Senate districts were redrawn in 2021. These districts were used as the basis for the general election held in November 2022. They took effect with the beginning of the subsequent General Assembly in January 2023. These districts will be used until December 2032.

IECAM will report data by post-Census 2020 districts for site-based services and most demographic variables from FY2023 (school year 2022–2023) through FY2032 (school year 2031–2032). In addition, IECAM will report data for site-based services according to these districts for 2021 and 2022 (years when those districts were not actually in effect) to provide a baseline comparison for later data. Demographic data for the Census 2020 districts will be available starting with the ACS 2022 estimates.

Illinois House Districts (post-2020 Census)

See also: Illinois House Districts post-2010 Census (legislative years 2013 through 2022)

Illinois Senate Districts (post-2020 Census)

See also: Illinois Senate Districts post-2010 Census  (legislative years 2013 through 2022)

Data available on IECAM

All site-based data (e.g., PFA, child care) and all demographic data (e.g., population) are presented by state House and Senate district on the IECAM database. Non-site-based data (e.g., early intervention, home visiting) are not presented by state House and Senate district.

Note on comparing legislative districts across decennial censuses: In IECAM’s online database and in the multiyear search feature, the legislative districts up through 2022 (the last year of districts based on the 2010 Census) will be considered one region type, and the legislative districts beginning in 2023 (the first year of districts based on the 2020 Census) will be considered another region type. Although the districts will have the same numbers for both region types, because the districts cover different geographic areas, they will not be comparable in the multiyear search feature. That is, you will not be able to compare the funded enrollment of Head Start in Senate District 52 in 2020 with the funded enrollment of Head Start in Senate District 52 in 2023. Because the geographic areas of the two examples of District 52 are not the same, such a comparison would be misleading.