Michigan Compiled Laws, Chapter 38. Civil Service and Retirement § 38.1502b

(a) A county, county road commission, city, village, or township.

(b) A public corporation or instrumentality established by 1 or more counties, cities, villages, or townships.

(c) A public corporation or instrumentality charged by law with the performance of a governmental function and whose jurisdiction is coextensive with 1 or more counties, cities, villages, or townships.

(d) A political subdivision located in this state or located in this and another adjacent state of the United States, including, but not limited to, the entities named in subdivision (a), (b), or (c), or any combination of those units.

(e) A political subdivision located in this state and a metropolitan government borough, or other political subdivision of the province of Ontario, an agency of the United States, or a similar entity of adjacent states of the United States and the province of Ontario.

(f) A state university, community college, or junior college whose employees are not public school employees who are members under the public school employees retirement act of 1979, 1980 PA 300, MCL 38.1301 to 38.1408.

(g) Any municipal corporation as defined in section 1(a) of 1951 PA 35, MCL 124.1, or other governmental entity that is eligible to join the retirement system and participate in any program under this act, as determined by the retirement board.