SS Badger is a passenger and vehicle ferry in the United States that has been in service on Lake Michigan since 1953. Currently, the ship shuttles between Ludington, Michigan, and Manitowoc, Wisconsin, a distance of 62 miles (100 km), connecting U.S. Highway 10 (US 10) between those two cities. She is the last coal-fired passenger vessel operating on the Great Lakes, and was designated a National Historic Landmark on January 20, 2016.

Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume and the third-largest by surface area, after Lake Superior and Lake Huron. To the east, its basin is conjoined with that of Lake Huron through the 3+1⁄2-mile (5.6-kilometer) wide, 295-foot deep Straits of Mackinac, giving it the same surface elevation as its easterly counterpart; geologically, the two bodies are a single lake that is, by area, the largest freshwater lake in the world.