ILL. COMP. STAT. ANN §220/2. Definitions
§ 2. Definitions. For the purpose of this Act:
(1) The term “public agency” shall mean any unit of local government as defined in the Illinois Constitution of 1970, any school district, any public community college district, any public building commission, the State of Illinois, any agency of the State government or of the United States, or of any other State, any political subdivision of another State, and any combination of the above pursuant to an intergovernmental agreement which includes provisions for a governing body of the agency created by the agreement.
For the purposes of this Act, “public agency” includes the Mid-America Intermodal Authority Port District created under the Mid-America Intermodal Authority Port District Act.
(2) The term “state” shall mean a state of the United States.
ILL. COMP. STAT. ANN §220/3. Intergovernmental cooperation. Any power or powers, privileges, functions, or authority exercised or which may be exercised by a public agency of this State may be exercised, combined, transferred, and enjoyed jointly with any other public agency of this State and jointly with any public agency of any other state or of the United States to the extent that laws of such other state or of the United States do not prohibit joint exercise or enjoyment and except where specifically and expressly prohibited by law. This includes, but is not limited to, (i) arrangements between the Illinois Student Assistance Commission and agencies in other states which issue professional licenses and (ii) agreements between the Department of Healthcare and Family Services (formerly Illinois Department of Public Aid) and public agencies for the establishment and enforcement of child support orders and for the exchange of information that may be necessary for the enforcement of those child support orders.
The link to the full statute can be found here: www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=92&ChapterID=2