(765 ILCS 205/1) (from Ch. 109, par. 1)
    Sec. 1. (a) Except as otherwise provided in subparagraph (b) of this Section whenever the owner of land subdivides it into 2 or more parts, any of which is less than 5 acres, he must have it surveyed and a subdivision plat thereof made by an Illinois Registered Land Surveyor, which plat must particularly describe and set forth all public streets, alleys, ways for public service facilities, ways for utility services and community antenna television systems, parks, playgrounds, school grounds or other public grounds, and all the tracts, parcels, lots or blocks, and numbering all such lots, blocks or parcels by progressive numbers, giving their precise dimensions. There shall be submitted simultaneously with the subdivision plat, a study or studies which shall show topographically and by profile the elevation of the land prior to the commencement of any change in elevations as a part of any phase of subdividing, and additionally, if it is contemplated that such elevations, or the flow of surface water from such land, will be changed as a result of any portion of such subdivision development, then such study or studies shall also show such proposed changes in the elevations and the flow of surface water from such land. The topographical and profile studies required hereunder may be prepared as a subsidiary study or studies separate from, but of the same scale and size as the subdivision plat, and shall be prepared in such a manner as will permit the topographical study or studies to be used as overlays to the subdivision plat. The plat must show all angular and linear data along the exterior boundaries of the tract of land divided or subdivided, the names of all public streets and the width, course and extent of all public streets, alleys and ways for public service facilities. References must also be made upon the plat to known and permanent monuments from which future survey may be made and the surveyor must, at the time of making his survey, set in such manner that they will not be moved by frost, good and sufficient monuments marking the external boundaries of the tract to be divided or subdivided and must designate upon the plat the points where they may be found. These monuments must be placed at all corners, at each end of all curves, at the point where a curve changes its radius, at all angle points in any line and at all angle points along a meander line, the points to be not less than 20 feet back from the normal water elevation of a lake or from the bank of a stream, except that when such corners or points fall within a street, or proposed future street, the monuments must be placed in the right of way line of the street. All internal boundaries, corners and points must be monumented in the field by like monuments as defined above. These monuments 2 of which must be of stone or reinforced concrete and must be set at the opposite extremities of the property platted, placed at all block corners, at each end of all curves, at the points where a curve changes its radius, and at all angle points in any line. All lots must be monumented in the field with 2 or more monuments.
    The monuments must be furnished by the person for whom the survey is made and must be such that they will not be moved by frost. If any city, village or town has adopted an official plan, or part thereof, in the manner prescribed by law, the plat of land situated within the area affected thereby must conform to the official plan, or part thereof.
    (b) Except as provided in subsection (c) of this Section, the provisions of this Act do not apply and no subdivision plat is required in any of the following instances:
        1. the division or subdivision of land into parcels
    
or tracts of 5 acres or more in size which does not involve any new streets or easements of access;
        2. the division of lots or blocks of less than 1 acre
    
in any recorded subdivision which does not involve any new streets or easements of access;
        3. the sale or exchange of parcels of land between
    
owners of adjoining and contiguous land;
        4. the conveyance of parcels of land or interests
    
therein for use as a right of way for railroads or other public utility facilities and other pipe lines which does not involve any new streets or easements of access;
        5. the conveyance of land owned by a railroad or
    
other public utility which does not involve any new streets or easements of access;
        6. the conveyance of land for highway or other public
    
purposes or grants or conveyances relating to the dedication of land for public use or instruments relating to the vacation of land impressed with a public use;
        7. conveyances made to correct descriptions in prior
    
conveyances;
        8. the sale or exchange of parcels or tracts of land
    
following the division into no more than 2 parts of a particular parcel or tract of land existing on July 17, 1959 and not involving any new streets or easements of access;
        9. the sale of a single lot of less than 5 acres from
    
a larger tract when a survey is made by an Illinois Registered Land Surveyor; provided, that this exemption shall not apply to the sale of any subsequent lots from the same larger tract of land, as determined by the dimensions and configuration of the larger tract on October 1, 1973, and provided also that this exemption does not invalidate any local requirements applicable to the subdivision of land;
        10. the preparation of a plat for wind energy devices
    
under Section 10-620 of the Property Tax Code.
    Nothing contained within the provisions of this Act shall prevent or preclude individual counties from establishing standards, ordinances, or specifications which reduce the acreage minimum to less than 5 acres, but not less than 2 acres, or supplementing the requirements contained herein when a survey is made by an Illinois Registered Land Surveyor and a plat thereof is recorded, under powers granted to them.
    (c) However, if a plat is made by an Illinois Registered Surveyor of any parcel or tract of land otherwise exempt from the plat provisions of this Act pursuant to subsection (b) of this Section, such plat shall be recorded. It shall not be the responsibility of a recorder of deeds to determine whether the plat has been made or recorded under this subsection (c) prior to accepting a deed for recording.
(Source: P.A. 99-78, eff. 7-20-15.)