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
SR-101 was formed in 1931 as a loop off SR-1 (now US-91) from Logan south to Hyrum and west to Wellsville. The road from Hyrum east to the Hardware Ranch was added to the state highway system in 1949 as State Route 242, and that route was extended south to SR-39 in 1965. The legislature redefined the Hyrum-area routes in 1969, taking SR-101 east from Wellsville to the Hardware Ranch over former SR-242, and returning the extension to SR-39 to local control. The leg of former SR-101 from Hyrum north to Logan became part of a new SR-165 at that time. On March 17, 1972, the roadway connecting the Hardware Ranch Visitors Center to SR-101 was added to the state route system as an addition to SR-101. The connector road was previously designated Collector Road 311.