(10 ILCS 92/20)

Sec. 20. Definitions; exceptions; deposit; description.

(a) In this Act, all counties, census tracts, blockgroups, and blocks are those that appear on maps published by the United States Bureau of the Census for the 2020 census.

(b) In this Act:

"Tract" means census tract. A census tract is identified by a number with up to 4 digits and an optional 2-digit suffix. Census tract numbers consist of 6 digits with an implied decimal point between the fourth and fifth digit, with leading zeroes for census tract numbers with less than 4 digits and trailing zeroes for census tract numbers without a suffix.

"Wd" means ward.

"Pct" means precinct as the precinct was configured on May 27, 2021.

(c) Legislative and Representative Districts created by this Act for the purpose of electing Senators to the Illinois Senate and Representatives to the Illinois House of Representatives shall not be altered by operation of any other law, ordinance, or resolution.

(d) In this Act, blocks are identified by a 15-digit number as follows:

(1) The first 2 digits are the state code, using American National Standards Institute INCITS 31:2009 codes.

(2) The next 3 digits are the county code, using American National Standards Institute INCITS 31:2009 codes.

(3) The next 6 digits are the census tract number.

(4) The last 4 digits are the block number.

(e) Any part of Illinois that has not been described as included in one of the Districts described in this Act is included within the District that (i) is contiguous to the part and (ii) contains the least population of all districts contiguous to the part according to the 2020 federal decennial census.

(f) If any part of Illinois is described in this Act as being in more than one District, the part is included within the District that (i) is one of the Districts in which that part is listed in this Act, (ii) is contiguous to that part, and (iii) contains the least population according to the 2020 federal decennial census.

(g) If any part of Illinois (i) is described in this Act as being in one District and (ii) is entirely surrounded by another District, then the part shall be incorporated into the District that surrounds the part.

(g-1) If any part of Illinois (i) is described in this Act as being in one District and (ii) is not contiguous to another part of that District, then the part is included within the contiguous District that contains the least population according to the 2020 federal decennial census.

(g-2) The Speaker of the House and the President of the Senate shall by joint letter of transmittal present to the Secretary of State for deposit into the State Archives an official set of United States Bureau of the Census 2020 geography maps, and those maps shall serve as the official record of all counties, census tracts, blockgroups, and blocks referred to in this Act.

(h) The State Board of Elections shall prepare and make available to the public a metes and bounds description of the Legislative and Representative Districts created under this Act as amended by this amendatory Act of the 102nd General Assembly.

(i) The Speaker of the House and the President of the Senate shall transmit to the Secretary of State detailed maps of each Legislative and Representative District as amended by this amendatory Act of the 102nd General Assembly. These maps will accurately depict the Legislative and Representative Districts as approved by the General Assembly.

(Source: P.A. 102-10, eff. 6-4-21; 102-663, eff. 9-24-21.)