The first major overland transportation corridors in the future state of Michigan were the Indian trails. Two of these trails are relevant to US 12. The St. Joseph Trail ran between the Benton Harbor–St. Joseph area and Detroit by way of what is now Kalamazoo, Battle Creek, Jackson, and Ann Arbor. The second, the Sauk Trail, ran further south through what is now Niles, and Coldwater to the Ann Arbor area.
