Mich. Comp. Laws § 213.194
Whenever the whole of a lot or parcel of land is, or has been, taken by any board or the commissioner, as provided in the preceding section, such board or commissioner, or his or their successors in office shall have the right, and are hereby authorized, to sell and convey the portion not needed, on whatever terms such board or commissioner may deem proper: Provided, That in those cases where the title to excess lands, acquired by the state highway commissioner under any law of this state, has been taken in the name of the state of Michigan, it shall be lawful for the state highway commissioner, and he is hereby authorized and empowered to sell and convey said lands as if the title thereto had originally been taken in his name as hereinbefore provided: And provided further, A record of all such sales, showing the appraised value, the sale price and other pertinent information, shall be kept in the office of the state highway commissioner.
MCL 213.194