Possible other merge and I-75 The part of I-75, originally US 2, between St. Ignace, Michigan, USA and the exit for Moran, Michigan, in the Upper Peninsula, was the first segment of freeway built in the UP. It was built in 1957 and coincided with the construction of other present-day segments of I-75 (Fenton-Clio Expressway and Detroit-Toledo Expressway). It never had an official name.

The original termini of this expressway were Castle Rock (near St. Ignace) and M-123 (near Moran). As I-75 closed its discontiguous gaps along with the construction of the Mackinac Bridge, this segment of freeway became part of I-75 and the national freeway system. US 2 ran concurrent with I-75 for a couple decades then US 2 was truncated to the south end to avoid duplication of signage.

When the US-2 freeway and the Mackinac Bridge had a gap present, the end of the highway feeding to/from the Mackinac Bridge had a simple trumpet junction at US-2. When that freeway gap was filled in, the ramp from the trumpet that headed from US-2 westbound to southbound converted to a ramp for (present-day I-75) northbound to reduce contrete/asphalt obliteration.