(765 ILCS 225/1) (from Ch. 133, par. 101) Sec. 1. This Act shall be known and may be cited as the "Illinois Coordinate System Act". (Source: P.A. 83-742.)

(765 ILCS 225/2) (from Ch. 133, par. 102) Sec. 2. The system of plane coordinates which has been established by the United States Department of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, National Geodetic Survey for defining and stating the positions or locations of points on the surface of the earth within the State of Illinois is hereinafter to be known and designated as the "Illinois Coordinate System". (Source: P.A. 92-311, eff. 8-9-01.)

(765 ILCS 225/3) (from Ch. 133, par. 103) Sec. 3. For the purpose of the use of the Illinois Coordinate System, the State is divided into an "East Zone" and a "West Zone". The area now included in the following counties constitutes the "East Zone": Boone, Champaign, Clark, Clay, Coles, Cook, Crawford, Cumberland, DeKalb, DeWitt, Douglas, DuPage, Edgar, Edwards, Effingham, Fayette, Ford, Franklin, Gallatin, Grundy, Hamilton, Hardin, Iroquois, Jasper, Jefferson, Johnson, Kane, Kankakee, Kendall, Lake, LaSalle, Lawrence, Livingston, McHenry, McLean, Macon, Marion, Massac, Moultrie, Piatt, Pope, Richland, Saline, Shelby, Vermilion, Wabash, Wayne, White, Will and Williamson. The area now included in the following counties constitutes the "West Zone": Adams, Alexander, Bond, Brown, Bureau, Calhoun, Carroll, Cass, Christian, Clinton, Fulton, Greene, Hancock, Henderson, Henry, Jackson, Jersey, Jo Daviess, Knox, Lee, Logan, McDonough, Macoupin, Madison, Marshall, Mason, Menard, Mercer, Monroe, Montgomery, Morgan, Ogle, Peoria, Perry, Pike, Pulaski, Putnam, Randolph, Rock Island, St. Clair, Sangamon, Schuyler, Scott, Stark, Stephenson, Tazewell, Union, Warren, Washington, Whiteside, Winnebago and Woodford. (Source: P.A. 98-756, eff. 7-16-14.)

(765 ILCS 225/4) (from Ch. 133, par. 104) Sec. 4. As established for use in the East Zone, the Illinois Coordinate System is named, the "Illinois Coordinate System, East Zone". As established for use in the West Zone, the Illinois Coordinate System is named, the "Illinois Coordinate System, West Zone". (Source: P.A. 83-742.)

(765 ILCS 225/5) (from Ch. 133, par. 105) Sec. 5. The plane coordinates of a point on the earth's surface, used in expressing the position or location of that point in the appropriate zone of this system, consists of 2 distances, expressed in units of U.S. survey feet and decimals of a foot. One of these distances, known as the "x-coordinate", gives the position in an east-and-west direction; the other, known as the "y-coordinate", gives the position in a north-and-south direction. These coordinates depend upon and conform to the coordinates, on the Illinois Coordinate System, of the monumented survey stations of the United States National Geodetic Survey within the State of Illinois, as those coordinates have been determined by that survey. (Source: P.A. 92-311, eff. 8-9-01.)

(765 ILCS 225/6) (from Ch. 133, par. 106) Sec. 6. When any project extends from one into the other of the above coordinate zones, the positions of all points on its boundaries may be referred to either of the two zones, the zone which is used being specifically named for the project. (Source: P.A. 83-742.)

(765 ILCS 225/7) (from Ch. 133, par. 107) Sec. 7. For purposes of more precisely defining the Illinois Coordinate System the following definitions by the United States National Geodetic Survey are adopted: The Illinois Coordinate System, East Zone, is based on the transverse Mercator projection of the North American Datum of 1983 (NAD 83) or the Clarke spheroid of 1866 (North American Datum of 1927) (NAD 27), having a central meridian of eighty-eight degrees and twenty minutes West (88µ =-20'W.) of Greenwich on which meridian the scale is set at one part in 40,000 too small. The origin of coordinates is at the intersection of the meridian eighty-eight degrees and twenty minutes West (88µ =-20'W.) of Greenwich and thirty-six degrees and forty minutes North (36µ =-40'N.) latitude. The origin is given the coordinates x = 300,000 meters (984,250.000 feet) and y = 0 meters for NAD 83 and x = 500,000 feet and y = 0 feet for the NAD 27. The Illinois Coordinate System, West Zone, is based on the transverse Mercator projection of the North American Datum of 1983 (NAD 83) or the Clarke spheroid of 1866 North American Datum of 1927 (NAD 27), having a central meridian of ninety degrees and ten minutes West (90µ =-10'W.) of Greenwich, on which meridian the scale is set at one part in 17,000 too small. The origin of coordinates is at the intersection of the meridian ninety degrees and ten minutes West (90µ =-10'W.) of Greenwich and thirty-six degrees and forty minutes North (36µ =-40'N.) latitude. The origin is given the coordinates x = 700,000 meters (2,296,583.333 feet) and y = 0 meters for NAD 83 and x = 500,000 feet and y = 0 feet for the NAD 27. The position of the Illinois Coordinate System is as marked on the ground by monumented survey stations established in conformity with standards adopted by the United States National Geodetic Survey for second and higher order work, whose geodetic positions have been rigidly adjusted on the North American Datum (NAD 1927 or NAD 1983, or both), and whose coordinates have been computed on the system herein defined. Any such stations may be used for establishing a survey connection with the Illinois Coordinate System. (Source: P.A. 92-311, eff. 8-9-01.)

(765 ILCS 225/8) (from Ch. 133, par. 108) Sec. 8. The use of the term "Illinois Coordinate System" on any map, report, survey, or other document is limited to coordinates based on the Illinois Coordinate System as defined in this Act. Any land survey referenced to the Illinois Coordinate System must indicate the Zone and delineate on the plat of survey all geodetic stations, azimuths, angles and distances used for establishing the survey connection. (Source: P.A. 83-742.)