Complex sentence: M-122 was a state trunkline highway in the US state of Michigan that junctioned with US 2 at St. Ignace and ran, entirely within St. Ignace, to the State Highway Ferry Dock used before the Mackinac Bridge was built.
Split into simpler sentences: M-122 was a state trunkline highway in the US state of Michigan entirely in the city of St. Ignace. The highway connected US Highway 2 (US 2) to the State Highway Ferry Dock used before the Mackinac Bridge was built.