Illinois Statutes § 5/11-3 Election precincts

(a) It shall be the duty of the Board of Commissioners established by Article 6 of this Act, within 2 months after its first organization, to divide the city, village or incorporated town which may adopt or is operating under Article 6, into election precincts, each of which shall be situated within a single congressional, legislative and representative district insofar as is practicable and in not more than one County Board district and one municipal ward; in order to situate each precinct within a single district or ward, the Board of Election Commissioners shall change the boundaries of election precincts after each decennial census as soon as is practicable following the completion of congressional and legislative redistricting and such precincts shall contain as nearly as practicable : (i) 1,200 registered voters if the precinct is located in a county with fewer than 3,000,000 inhabitants; or (ii) 1,800 registered voters if the precinct is located in a county with 3,000,000 or more inhabitants [600 qualified voters, and in making such division and establishing such precincts such board shall take as a basis the poll books, or the number of votes cast at the previous presidential election] .

(b) Within 90 days after each presidential election, such board in a city with fewer than 500,000 inhabitants, village or incorporated town shall revise and rearrange such precincts on the basis of the votes cast at such election, making such precincts to contain, as near as practicable, 1,200 registered voters or 1,800 registered voters, as applicable [600 actual voters; but at any time in all instances where the vote cast at any precinct, at any election, equals 800, there must be a rearrangement so as to reduce the vote to the standard of 600 as near as may be] . However, any apartment building in which more than 1,200 or 1,800 [800] registered voters , as applicable, reside may be made a single precinct even though the vote in such precinct exceeds 1,200 or 1,800 registered voters, as applicable [800] .

(c) Within 90 days after each presidential election, a board in a city with more than 500,000 inhabitants shall revise and rearrange such precincts on the basis of the votes cast at such election, making such precincts to contain, as near as practicable : (i) 1,200 registered voters if the precinct is located in a county with fewer than 3,000,000 inhabitants; or (ii) 1,800 registered voters if the precinct is located in a county with 3,000,000 or more inhabitants [, 400 actual voters; but at any time in all instances where the vote cast at any precinct, at any election, equals 600, there must be a rearrangement so as to reduce the vote to the standard of 400 as near as may be] . However, any apartment building in which more than 1,200 registered voters or 1,800 registered voters, as applicable, [600 registered voters] reside may be made a single precinct even though the vote in such precinct exceeds 1,200 or 1,800 registered voters, as applicable [600] .

(d) Immediately after the annexation of territory to the city, village or incorporated town becomes effective the Board of Election Commissioners shall revise and rearrange election precincts therein to include such annexed territory.

(e) Provided, however, that at any election where but one candidate is nominated and is to be voted upon at any election held in any political subdivision of a city, village or incorporated town, the Board of Election Commissioners shall have the power in such political subdivision to determine the number of voting precincts to be established in such political subdivision at such election, without reference to the number of qualified voters therein. The precincts in each ward, village or incorporated town shall be numbered from one upwards, consecutively, with no omission.

(f) The provisions of this Section apply to all precincts, including those where voting machines or electronic voting systems are used.