U.S. Route 101
The nearly highway's northern terminus is in Tumwater, Washington: the route remains along the Olympic Peninsula's coastal perimeter west, north, and east; the northernmost point on the highway is in Port Angeles. The southern terminus of US 101 is in Los Angeles at the East Los Angeles Interchange, the world's busiest freeway interchange.
Utah State Route 101
Located entirely in Cache County, SR-101 starts at an intersection of Main Street and SR-23 (Center Street) in Wellsville. The highway heads easterly for the first before it turns northeasterly, crossing the Little Bear River and intersects US-89/US-91 at a traffic light controlled at-grade interchange. After the interchange, SR-101 turns to the southeast after entering Hyrum city limits. At 400 West, SR-101 turns south for 3 blocks before turning back to the east, and intersecting SR-165.