Michigan Compiled Laws, Chapter 600. Revised Judicature Act of 1961 § 600.8103

Sec. 8103. (1) A district of the first class is a district consisting of 1 or more counties and in which each county comprising the district is responsible for maintaining, financing and operating the district court within its respective county except as otherwise provided in this act.

(2) A district of the second class is a district consisting of a group of political subdivisions within a county and in which the county where such political subdivisions are situated is responsible for maintaining, financing and operating the district court except as otherwise provided in this act.

(3) A district of the third class is a district consisting of 1 or more political subdivisions within a county and in which each political subdivision comprising the district is responsible for maintaining, financing and operating the district court within its respective political subdivision except as otherwise provided in this act.