65 ILCS 5/ Illinois Municipal Code.

(65 ILCS 5/11-12-9) (from Ch. 24, par. 11-12-9)

Sec. 11-12-9. If unincorporated territory is within one and one-half miles of the boundaries of two or more corporate authorities that have adopted official plans, the corporate authorities involved may agree upon a line which shall mark the boundaries of the jurisdiction of each of the corporate authorities who have adopted such agreement. On and after September 24, 1987, such agreement may provide that one or more of the municipalities shall not annex territory which lies within the jurisdiction of any other municipality, as established by such line. In the absence of such a boundary line agreement, nothing in this paragraph shall be construed as a limitation on the power of any municipality to annex territory. In arriving at an agreement for a jurisdictional boundary line, the corporate authorities concerned shall give consideration to the natural flow of storm water drainage, and, when practical, shall include all of any single tract having common ownership within the jurisdiction of one corporate authority. Such agreement shall not become effective until copies thereof, certified as to adoption by the municipal clerks of the respective municipalities, have been filed in the Recorder's Office and made available in the office of the municipal clerk of each agreeing municipality.

Any agreement for a jurisdictional boundary line shall be valid for such term of years as may be stated therein, but not to exceed 20 years, and if no term is stated, shall be valid for a term of 20 years. The term of such agreement may be extended, renewed or revised at the end of the initial or extended term thereof by further agreement of the municipalities.

In the absence of such agreement, the jurisdiction of any one of the corporate authorities shall extend to a median line equidistant from its boundary and the boundary of the other corporate authority nearest to the boundary of the first corporate authority at any given point on the line.

On and after January 1, 2006, no corporate authority may enter into an agreement pursuant to this Section unless, not less than 30 days and not more than 120 days prior to formal approval thereof by the corporate authority, it shall have first provided public notice of the proposed boundary agreement by both of the following:

(1) the posting of a public notice for not less than 15 consecutive days in the same location at which notices of village board or city council meetings are posted; and

(2) publication on at least one occasion in a newspaper of general circulation within the territory that is subject to the proposed agreement.

The validity of a boundary agreement may not be legally challenged on the grounds that the notice as required by this Section was not properly given unless the challenge is initiated within 12 months after the formal approval of the boundary agreement.

An agreement that addresses jurisdictional boundary lines shall be entirely unenforceable for any party thereto that subsequently enters into another agreement that addresses jurisdictional boundary lines that is in conflict with any of the terms of the first agreement without the consent of all parties to the first agreement. For purposes of this Section, it shall not be considered a "conflict" when a municipality that is a party to a jurisdictional boundary line agreement cedes property within its own jurisdiction to another municipality not a party to the same jurisdictional boundary line agreement.

This amendatory Act of 1990 is declarative of the existing law and shall not be construed to modify or amend existing boundary line agreements, nor shall it be construed to create powers of a municipality not already in existence.

Except for those provisions to take effect prospectively, this amendatory Act of the 94th General Assembly is declarative of existing law and shall not be construed to modify or amend existing boundary line agreements entered into on or before the effective date of this amendatory Act, nor shall it be construed to create powers of a municipality not already in existence on the effective date of this amendatory Act.

(Source: P.A. 99-292, eff. 8-6-15.)

(65 ILCS 5/11-12-10) (from Ch. 24, par. 11-12-10)

Sec. 11-12-10. The provisions of this amendatory Act of 1961 shall not affect the validity of any official plan or map adopted and in force prior to the effective date hereof.

(Source: Laws 1961, p. 2757.)

(65 ILCS 5/11-12-11) (from Ch. 24, par. 11-12-11)

Sec. 11-12-11. If a municipality has adopted an official plan or map pursuant to the authority granted by this Division 12, the territory subject to that plan shall be exempt from the application of any less restrictive rules or regulations adopted by a County Board under the provisions of Section 5-1042 of the Counties Code.

(Source: P.A. 86-1475.)

(65 ILCS 5/11-12-12) (from Ch. 24, par. 11-12-12)

Sec. 11-12-12. No map or plat of any subdivision presented for record affecting land (1) within the corporate limits of any municipality which has heretofore adopted, or shall hereafter adopt an ordinance including an official map in the manner prescribed in this Division 12, or (2) within contiguous territory which is not more than 1 1/2 miles beyond the corporate limits of an adopting municipality, shall be entitled to record or shall be valid unless the subdivision shown thereon provides for streets, alleys, public ways, ways for public service facilities, storm and flood water run-off channels and basins, and public grounds, in conformity with the applicable requirements of the ordinances including the official map; provided, that a certificate of approval by the corporate authorities, certified by the clerk of the municipality in whose jurisdiction the land is located, or a certified copy of an order of the circuit court directing the recording as provided in Section 11-12-8, shall be sufficient evidence of compliance with this section upon which the recorder may accept the plat for recording.

The provisions of this Section do not apply to any plat for consolidation of 2 or more contiguous parcels, located within any territory that is outside of the corporate limits of a municipality but within a county that has adopted a subdivision ordinance and that has a population of more than 250,000, into a smaller number of parcels if the sole purpose of the consolidation is to bring a non-conforming parcel into conformance with local zoning requirements. The exemption created by this amendatory Act of the 92nd General Assembly does not apply to a plat for consolidation for an area in excess of 10 acres or to any consolidation that results in a plat of more than 10 individual lots following the consolidation. If the county receives a request to approve a plat for consolidation pursuant to this Section, the county must notify all municipalities located within 1 1/2 miles of the subject property within 10 days after receiving the request.

(Source: P.A. 92-361, eff. 1-1-02.)

(65 ILCS 5/11-12-13)

Sec. 11-12-13. Joint plan commissions. Whenever the corporate authorities of 2 or more municipalities having a population less than 500,000 determine that unincorporated land and territory lying adjacent to any one or more of such municipalities, or land and territory comprising a portion of such municipalities, or land and territory both lying adjacent to such municipalities and being a part of such municipalities forms a contiguous region and such land and territory (i) is or was formerly owned by the United States of America or any department thereof, (ii) is located entirely within a county having a population of not less than 500,000 nor more than 1,000,000 persons, (iii) has been annexed or is intended to be annexed to one or more of such municipalities, and (iv) comprises not less than 500 nor more than 800 acres, the said corporate authorities are hereby empowered, by intergovernmental agreement between or among the municipalities, to define the boundaries of such region and to create a joint plan commission having one, some, or all of the powers set forth in this Section.

(1) Membership of joint plan commissions. The joint plan commission shall consist of such number of persons known as "members" as shall be set forth in the intergovernmental agreement. The parties, acting by and through their mayors or village presidents with the advice and consent of each of their respective corporate authorities, shall appoint the members who shall hold office as set forth in such intergovernmental agreement. If authorized to do so by such intergovernmental agreement, the joint plan commission may employ a staff to assist in the administration and enforcement of zoning and building codes or ordinances throughout the region.

(2) Powers and duties of joint plan commissions. The corporate authorities by such intergovernmental agreement may provide for the joint plan commission to have all or some of the functions, powers and duties contained in Divisions 12, 13, 14, and 15 of this Article 11 of this Code.

(a) The joint plan commission shall be a recommendatory body only and all recommendations thereof shall be advisory to all of the corporate authorities of the municipalities which have entered into such intergovernmental agreement and affect only that incorporated land and territory of the region lying within the corporate limits of such municipalities.

(b) Such intergovernmental agreement may further authorize such joint plan commission exclusive jurisdiction to apply and enforce the respective zoning and building codes and other applicable codes of each municipality concerning the land within the region lying within the respective corporate limits of such municipality and may provide for immediate removal of such region from the jurisdiction of such municipalities' plan commissions, zoning boards of appeal, and other bodies or officials authorized to exercise such powers and duties.

(c) Such intergovernmental agreement may authorize such joint plan commission to establish rules and procedures consistent with this Section as may be necessary to carry out the terms of such intergovernmental agreement.

(3) Conflict resolution.

(a) In order to become effective in matters within its jurisdiction, a recommendation of any such joint plan commission pursuant to this Section shall require the approval set forth in the intergovernmental agreement. The intergovernmental agreement creating a joint plan commission shall establish procedures for the consideration and approval or disapproval by such municipalities of the joint plan commission's recommendation, and for the resolution between or among the municipalities of disputes or differences arising from any recommendation of the joint plan commission. Once effective, any such recommendation regarding rezoning, variations, or special uses shall require the adoption of a suitable ordinance by the corporate authorities of only that municipality within whose corporate limits lies the land and territory which is the subject of such recommendation.

(b) Any party to such intergovernmental agreement may by civil action, mandamus, injunction or other proceeding, enforce and compel performance of the agreement.

This amendatory Act of 1996 shall not be a limitation on home rule powers.

(Source: P.A. 89-666, eff. 8-14-96.)