Fort Gratiot Light in Port Huron marks the entrance where Lake Huron narrows into the St. Clair River, a vital passage for Great Lakes shipping. Built in 1825, it was Michigan’s first lighthouse and is the state’s oldest surviving one. Its first tower proved poorly built, collapsed after storm damage, and was replaced in 1829 by a larger structure later raised in 1862 as traffic increased. Improvements from the Lewis lamp to Fresnel lenses strengthened its role as an active navigational aid. Expanded over time with keepers’ housing, fog signals, and Coast Guard facilities, it also became a preserved public historic site offering seasonal tours.