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.
U.S. Route 91
At its peak, from 1947 to 1965, U.S. 91 extended from the Pacific Ocean at Long Beach, California to Coutts, Alberta. North of Riverside, California, U.S. 91 followed a route that would be largely paralleled by modern I-15 and I-215 where these routes did not completely supplant it. There are some parts where U.S. 91/I-15 had divergent paths. The more southerly is from Littlefield, Arizona to St. George, Utah where the two routes took different paths through the Arizona Strip. The more northerly and longer is the surviving portion of U.S. 91 from Brigham City to Downey, where Interstate 15 follows an old route of U.S. Route 191.