Michigan Compiled Laws, Chapter 45. Counties § 45.21

Sec. 21.  When a county possessed of, or entitled to money, rights, credits, things in action or personal property, shall be so divided or altered, or when any unorganized county or district annexed to any county for judicial purposes, shall be organized into a separate county, such money, rights, credits, things in action or personal property, shall be adjusted and apportioned, and a settlement thereof made between the counties interested therein, by the supervisors thereof, as to them or a majority of them shall appear to be just and equitable.