The first section of freeway was built in late 1957 or early 1958 between Evergreen Shores and M ‑ 123 north of St. Ignace . The Mackinac Bridge was opened to traffic on November 1 , 1957 ; a new section of freeway and an interchange connected US 2 to the bridge . In 1961 , another new freeway segment closed the gap between the Mackinac Bridge and Evergreen Shores sections . At the time , the I ‑ 75 designation supplanted US 27 on the bridge , and US 2 was shifted to follow I ‑ 75 along the freeways in the St. Ignace area . The former routing of US 2 in downtown St. Ignace was redesignated BL I ‑ 75 . More sections of freeway were opened in 1962 immediately to the south of the newly constructed International Bridge in Sault Ste . Marie as well as between Dafter and Kinross . The last two sections opened in 1963 connected the northern end of the freeway at M ‑ 123 to Kinross , and the section between Dafter and Sault Ste . Marie . At this time , all of US 2 's former routing became a county road known as Mackinac Trail ( H @-@ 63 ) .