While the official western terminus of US 212 is at the Northeast Entrance of Yellowstone National Park near the Wyoming–Montana state line, some commercially produced maps show the highway within the park itself, contiguous with Northeast Entrance Road, starting from its western end at Tower Junction on the Grand Loop.

[2] Within the Crow Indian Reservation, US 212 leaves I-90 and runs east and southeast through the high plains of Montana.

Southeast of Alzada, US 212 recrosses the Wyoming state line; after about 20.3 miles (32.7 km), US 212 enters South Dakota.

Here it intersects US 85, and then continues eastward, skirting the southern end of the Belle Fourche Reservoir.

It runs north into Newell, then turns generally east again, passing through the town of Faith and entering the Cheyenne River Indian Reservation.

The route in Minnesota connects the cities of Montevideo, Granite Falls, Olivia, Glencoe, Norwood Young America, and the southwest suburbs of Minneapolis.