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 101
Parts of Historic US 101 can still be found in San Diego County between Oceanside and the border with Mexico under a variety of different names. Through Oceanside it is called Coast Highway. In Carlsbad it becomes Carlsbad Boulevard, but to the south in Encinitas it is Coast Highway 101. Solana Beach keeps it consistent with Highway 101, but Del Mar changes it to Camino Del Mar. All of those together make up CR S21. From there it continues along Torrey Pines Road, La Jolla Village Dr and Gilman Dr to merge with I-5 in La Jolla. On I-5, it breaks away from the freeway to follow Mission Bay Dr (former I-5 bus.) before rejoining I-5. The old US 101 routing continues on I-5 in San Diego until Pacific Highway, the old US 101 freeway a little west of current I-5. It then continued on Harbor Drive and Broadway through Downtown San Diego and Chula Vista, then onto National City Boulevard in National City. As it returns to San Diego on its way to the Mexican border, it follows Beyer Blvd through Otay Mesa and then through other parts of San Diego near the border on east Beyer Blvd and east San Ysidro Blvd in San Ysidro. The southern parts of I-5 were US 101 for a period before I-5 was completed also. All have been decommissioned, but the roadways still exist and are occasionally signed as Historic 101.