U.S. Route 101

U.S. Route 101, or U.S. Highway 101 (US 101), is a north–south United States Numbered Highway that traverses the states of California, Oregon, and Washington, on the West Coast of the United States. It travels for over 1,500 miles (2,400 km), primarily along the Pacific Ocean, and is also known by various names, including El Camino Real (The Royal Road) in parts of California, the Oregon Coast Highway, and the Olympic Highway in Washington. Despite its three-digit number, normally used for spur routes, US 101 is classified as a major route in the United States Numbered Highway System.

The highway's southern terminus is at a major interchange with Interstate 5 (I-5) and I-10 in Los Angeles. US 101 follows several freeways in Southern California as it travels north of the Santa Monica Mountains and along the coast, where it is concurrent with California State Route 1 (SR 1). The highway travels inland from the coast after it splits from SR 1 and approaches the San Francisco Bay Area, where it becomes the Bayshore Freeway and later traverses San Francisco on city streets to reach the Golden Gate Bridge. US 101 continues north and rejoins the coast on the Redwood Highway before it enters Oregon.

The Oregon Coast Highway carries US 101 through the state's coastal towns and regions in the foothills of the Oregon Coast Range. The highway crosses over the Columbia River on the Astoria–Megler Bridge into Washington, where it follows Willapa Bay and an inland route to Aberdeen and Olympic National Park. US 101 travels north and east around the Olympic Peninsula and reaches its northernmost point in Port Angeles; from there, it travels east and later south to its northern terminus at I-5 in Tumwater, Washington, near Olympia, Washington. Several portions of the highway are also designated as scenic byways, including the Pacific Coast Scenic Byway in Washington; US 101 also serves three national parks: Pinnacles, Redwood, and Olympic.

US 101 is a major north–south link along the Pacific coast north of San Francisco, but does not serve the largest cities in Oregon and Washington; that role is instead filled by I-5, which has a more direct routing. The highway provides a major parallel route between Los Angeles and San Francisco, with significant freeway portions. US 101 was established in 1926 and followed several historic routes, including El Camino Real, which linked California's early Spanish missions, pueblos, and presidios. It originally terminated to the south in San Diego, but was truncated to Los Angeles in 1964 after the construction of I-5. Other sections were later moved to freeway alignments that bypassed cities.