U.S. Route 101
U.S. Route 101, or U.S. Highway 101 (US 101) is a north–south United States Numbered Highway that runs through the states of California, Oregon, and Washington, on the West Coast of the United States. It is also known as (The Royal Road) where its route along the southern and central California coast approximates the old trail which linked the Spanish missions, pueblos, and presidios. It merges at some points with California State Route 1 (SR 1).
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.