U.S. Route 89 is a north–south United States Highway with two sections, and one former section. The southern section runs for 848 miles (1,365 kilometers) from Flagstaff, Arizona, to the southern entrance of Yellowstone National Park. The northern section runs for 404 miles (650 kilometers) from the northern entrance of Yellowstone National Park to Montana, ending at the Canadian border. An implied route through Yellowstone connects the two sections. Before 1992, U.S. Highway 89 was a Canada to Mexico, border-to-border, highway that ended at Nogales, Arizona on its southern end.

Sometimes called the National Park Highway, U.S. 89 links seven National Parks across the Mountain West. In addition, fourteen other National Park areas, mostly National Monuments are also reachable from this backbone of the rockies.