High Quality Content by WIKIPEDIA articles! Saginaw Trail is the collective name for a set of connected roads in Southeastern Michigan that runs from Detroit to Saginaw through Pontiac and Flint. It was originally a tribal foot trail. On December 7, 1818 the Michigan Territorial government authorized the building of a road from Detroit to Saginaw along the trail. The road has gone through a number of designation changes in the last two centuries, both in name and number. Since the Michigan portion of Interstate 75 (I-75) was completed in 1973, it has been a secondary route.