U.S. Federal Route 12 runs east-west across Hillsdale County. It runs from the Branch/Hillsdale County Line, near Allen, to the Lenawee/Hillsdale County Line, near Somerset. U.S. Rt. 12 passes through the following towns in Hillsdale County. Allen
Jonesville Moscow Somerset Center Somerset U.S. Rt. 12 is multi-plexed in Hillsdale County. Michigan State Route 49, at Allen.