U.S. 212 (Montana)
Credit: Alamy

Spanning four states, a thousand miles, and a nosebleed's worth of elevation changes, U.S. 212 is one of those highways that's difficult to describe in a single (non-run-on) sentence. The single section of this road that runs from Yellowstone National Park across the state of Montana packs in as many rollicking good times as most interstates in their entirety. The Beartooth section, which extends from Red Lodge to Cooke City Montana (and dips into Wyoming) is particularly challenging with its steep, switchbacked sections, and sometimes snowy conditions, but foolhardy motorists are rewarded with what chronic road warrior Charles Kuralt once pronounced, "The most beautiful drive in America."