Mich. Comp. Laws § 397.133

Sec. 3. A library shall maintain a collection of at least 1,000,000 volumes in order to be eligible for membership in the network. A library shall be connected to the state library by means of electronic equipment and shall agree to supply for interlibrary loan any volume in its collection, not in use, except rare volumes, reference works, books on reserve for course work, volumes of serials, fragile materials, and all other library materials which are not loaned under its regulations.