U.S. Route 212 (US 212) is a part of the U.S. Highway System that travels from Yellowstone National Park east to Edina, Minnesota. In South Dakota, it starts at the Wyoming state line northeast of Belle Fourche and extends approximately to the Minnesota state line east of Goodwin.
US 212 enters South Dakota near the Wyoming state line, southeast of the Montana state line, and continues southeast to Belle Fourche. Here it intersects US 85, and then continues eastward, skirting the southern end of the Belle Fourche Reservoir. It continues east for , passing Nisland, until intersecting with South Dakota Highway 79 (SD 79) where they are briefly cosigned until Newell. US 212 continues east, passing through Faith, and enters the Cheyenne River Indian Reservation, where it continues through Dupree and North Eagle Butte, and reaches the Lake Oahe, a reservoir on the Missouri River.
US 212 crosses the Missouri River, leaving the Cheyenne River Indian Reservation, and travels east where it intersects (and briefly co-signed) US 83 near Gettysburg. US 212 continues eastward for through Gettysburg, Seneca, and Faulkton before reaching SD 45, where they are cosigned and turn south for , before continuing eastward for , passing through Rockham and Zell before reaching Redfield where it intersects with US 281.
Continuing east for , US 212 passes through Frankfort, Doland, Clark, and Henry before passing the southern edge of Lake Kampeska and entering Watertown. US 212 follows 9th Avenue S, intersecting US 81 near the downtown area and Interstate 29 on the city's eastern edge. US 212 continues east for , passing through Krazburg and Goodwin, before crossing into Minnesota.
Legally, the South Dakota section of US 212 is defined at South Dakota Codified Laws ç 31-4-206.
Highway 212 Business (US 212 Bus.) in Belle Fourche, is a unofficial route that goes into the downtown area of Belle Fourche. It is not signed with a US Highway shield and is not a state-maintained highway.