Mich. Comp. Laws § 257.971

Sec. 1. As used in this act: (a) "Public transportation vehicles" means vehicles having a passenger capacity of 9 or more operating as part of a public transportation system within and not more than 10 miles from the boundaries of a municipality or not beyond the county or transportation regional boundaries when the vehicles are operated by a private person, firm, or corporation. (b) "City, intercity, and suburban bus operator" means any person, firm, or corporation operating 1 or more motor buses in this state having a seating capacity of 10 or more passengers under a franchise from a municipality, under a license granted by a municipality, or pursuant to an agreement entered into between the person, firm, or corporation and a municipality of this state, or a certificate of public convenience and necessity issued by the Michigan public service commission under section 5 of article 2 of Act No. 254 of the Public Acts of 1933, being section 476.5 of the Michigan Compiled Laws, and which is engaged in the transportation of passengers in and between 1 or more cities or villages or engaged in the transportation of passengers over regularly scheduled routes under a certificate of public convenience and necessity.