U.S. Route 101

U.S. Route 101, or U.S. Highway 101, is a major north–south highway that traverses the states of California, Oregon, and Washington on the West Coast of the United States. It is part of the United States Numbered Highway System and runs for over along the Pacific Ocean. The highway is also known by various names, including El Camino Real 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 primary route with 10 as its "first digit".
The highway's southern terminus is at a major interchange with Interstate 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. 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 on the Redwood Highway and rejoins the coast 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, near Olympia. 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.
The highway 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 inland routing. 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. Several sections of US 101 in Washington and Oregon were rebuilt in the mid-20th century to eliminate curves and address traffic congestion. Later projects expanded the Bayshore Freeway in the San Francisco Bay Area and relocated sections of the highway in Oregon in response to landslides and erosion.

Route description

California

US 101 travels on several major freeways in the Greater Los Angeles area, including some of the most congested roads in the United States. Its southern terminus is in Boyle Heights at the East Los Angeles Interchange, one of the busiest freeway junctions in the United States, where US 101 meets I-5, I-10, and SR 60. The highway travels north on a section of the Santa Ana Freeway and turns west to cross the Los Angeles River after merging with the San Bernardino Freeway. The Santa Ana Freeway continues across Downtown Los Angeles and passes Union Station, a major transit hub, and government buildings before it reaches a junction with SR 110. Beyond Downtown Los Angeles, US 101 uses the Hollywood Freeway as it travels northwest through the eponymous neighborhood towards Cahuenga Pass, where it crosses the Hollywood Hills and passes Universal Studios Hollywood. The highway leaves the Hollywood Freeway to turn west onto the Ventura Freeway, which travels along the southern edge of the suburban San Fernando Valley and intersects I-405. US 101 continues into Ventura County, where it joins SR 1 and serves communities in the Conejo Valley and Oxnard Plain.
The highway follows the Pacific Ocean northwest from Ventura through Santa Barbara, where it separates the downtown from its beach, and Goleta. US 101 becomes a divided highway beyond Goleta as it turns north at Gaviota State Park to cross the Santa Ynez Mountains at Gaviota Pass; SR 1 splits to remain closer to the coastline, as it does in several areas of the state. The highway continues inland and travels around the Purisima Hills to reach Santa Maria, where the freeway resumes as it bypasses the city. US 101 briefly returns to the coastline near Pismo Beach and turns inland over the Irish Hills towards San Luis Obispo alongside SR 1. The highway crosses the Santa Lucia Range through Cuesta Pass and follows the Salinas River northwest through Atascadero and the wine-growing region surrounding Paso Robles. US 101 passes near Pinnacles National Park and travels through the city of Salinas, where it turns northeast to cross the Gabilan Range. From there, the highway descends into the Santa Clara Valley and Gilroy, the southernmost city in the San Francisco Bay Area.
US 101 continues northwest into San Jose on the South Valley Freeway and later the Bayshore Freeway, which travels around the east and north sides of downtown San Jose. The ten-lane freeway generally follows the west side of San Francisco Bay as it traverses several Silicon Valley communities, including Palo Alto, Redwood City, and San Mateo, and passes offices for high-tech companies. It parallels I-280, which travels along the foothills of the Santa Cruz Mountains to the west, as the two continue up the San Francisco Peninsula. US 101 passes San Francisco International Airport and briefly turns northeast to rejoin the coastline before it enters the city of San Francisco near Candlestick Point. The Bayshore Freeway intersects I-280 and terminates at an interchange with I-80 near the SoMa neighborhood in the city center. US 101 then uses city streets to continue through San Francisco; it travels north on Van Ness Avenue, a wide boulevard with bus lanes, and west on Lombard Street to the Presidio of San Francisco, a historic landmark and city park.
File:Golden Gate Bridge as seen from Marshall's Beach, March 2018.jpg|thumb|left|The Golden Gate Bridge connects sections of US 101 between San Francisco and Marin County.|alt=The Golden Gate Bridge, a two-tower suspension bridge painted a dull orange, seen on a sunny day from a beach with mist over the water.
The divided highway travels through the north side of the Presidio and tunnels under a portion of the park as it approaches the Golden Gate Bridge, a tolled suspension bridge across the Golden Gate at the entrance to San Francisco Bay. It is operated by the Golden Gate Bridge, Highway and Transportation District and is not legally defined as part of US 101 and SR 1. The orange-colored bridge, considered an icon of the city, has six lanes with a movable barrier and walkways on both sides for pedestrians and cyclists. North of the bridge, US 101 is designated as the Redwood Highway. It splits from SR 1 and continues as an eight-lane freeway through suburban communities in Marin County, including an elevated viaduct in downtown San Rafael. The highway continues along the west side of San Pablo Bay into Sonoma County, where it turns northwest to head inland through Petaluma and Santa Rosa in the North Bay's Wine Country. US 101 follows the Russian River upstream through wineries and vineyards into Mendocino County as the freeway narrows to four lanes and eventually ends.
Beyond the San Francisco Bay Area, US 101 is primarily an undivided highway with some short freeway sections and serves as the primary route in the rugged North Coast region. It traverses the Mendocino Range and reaches the northern terminus of SR 1 at Leggett. The Redwood Highway then follows the South Fork Eel River north into Humboldt Redwoods State Park, where it runs parallel to the Avenue of the Giants. US 101 continues northwest along the Eel River to reach the coastline near Eureka, which it travels through on city streets before becoming a divided highway around Humboldt Bay. The highway travels north along the coast through the Redwood National and State Parks, where it passes through old-growth coast redwood forests, and reaches Crescent City. US 101 intersects US 199 north of the city and continues northwest along the coast to the Oregon state line.

Oregon

The Oregon Coast Highway begins at the California state line near Brookings and carries US 101 north along the Pacific coast. It is generally a two-lane highway that passes through small towns and near 77 state parks on the rugged coastline, as well as some inland areas. From Brookings, US 101 traverses the Samuel H. Boardman State Scenic Corridor, which includes roadside viewpoints and trailheads that face the ocean. The highway remains elevated from the coastline and briefly descends to sea level near the Pistol River State Scenic Viewpoint before climbing Cape Sebastian on its way to Gold Beach. US 101 travels through Gold Beach and crosses the Rogue River to continue north along the coast. The highway turns west to follow the base of Humbug Mountain, a mountain that rises from the Pacific Ocean, and northwest to reach Port Orford, where it leaves the coastline.
US 101 continues north, separated from the coastline by prairies and marshes, to Bandon; there, it briefly turns east and crosses the Coquille River to traverse more marshes. The highway travels further inland to the northeast and follows a slough off Coos Bay to the neighboring cities of Coos Bay and North Bend, where it splits into a pair of one-way streets. US 101 leaves North Bend and crosses Coos Bay on the Conde McCullough Memorial Bridge; from there, it heads north along the edge of a exposed coastal sand dune that forms the Oregon Dunes National Recreation Area, along with freshwater lakes to the east. US 101 diverts northeast to cross the Umpqua River at Reedsport and passes through a meandering section near Tahkenitch Lake before it returns to the coastal dunes around Dunes City.
The Oregon Coast Highway crosses the Siuslaw River into Florence and intersects Oregon Route 126, a major east–west route that traverses the Coast Range to Eugene. US 101 returns to the coastline near the Heceta Head Lighthouse and continues north along several high cliffs around Cape Perpetua and Yachats that overlook the beaches. The Oregon Coast Highway then crosses the Yaquina Bay Bridge into Newport and serves as the western terminus of US 20, a transcontinental route to Boston and the longest highway in the United States. US 101 continues along the coastline and Siletz Bay into Lincoln City, where it serves as the city's main street for and turns away from the coast to bypass the Cascade Head biosphere reserve. The highway briefly returns to the coastline before beginning a long inland stretch that follows the Nestucca River and other streams to Tillamook.
US 101 passes the Tillamook County Creamery Association factory and travels northwest along Tillamook Bay to rejoin the coast near Garibaldi, but later turns inland to skirt Nehalem Bay and avoid Cape Falcon. The highway travels around the community of Cannon Beach, home to the landmark Haystack Rock, and turns northeast to bypass Tillamook Head and intersect US 26—a major route to Portland. US 101 continues north along the Necanicum River to reach the coast at Seaside and travel through the city and nearby beach communities. The highway turns northeast and crosses Youngs Bay from Warrenton to Astoria, where it meets the western terminus of US 30; that highway continues into downtown Astoria and east towards Portland. US 101 turns south onto a loop ramp that leads north to the Astoria–Megler Bridge, a bridge that spans the mouth of the Columbia River and carries the highway into Washington.