Mich. Comp. Laws § 252.8

Sec. 8. Each participating county shall pay annually into the treasury of said commission such sums as shall have been agreed upon under contract executed pursuant to section 1 hereof, and such additional sums as may from time to time be approved by a majority vote of the members elect of the board of supervisors of each county. The sums of money so received shall together constitute the inter-county highway fund which shall be disbursed as said commission may determine.