State Route 1 (SR 1) is a major north–south state highway that runs along most of the Pacific coastline of the U.S. state of California. At , it is the longest state route in California, and the second-longest in the US after Montana Highway 200. SR 1 has several portions designated as either Pacific Coast Highway (PCH), Cabrillo Highway, Shoreline Highway, or Coast Highway. Its southern terminus is at Interstate 5 (I-5) near Dana Point in Orange County and its northern terminus is at U.S. Route 101 (US 101) near Leggett in Mendocino County. SR 1 also at times runs concurrently with US 101, most notably through a stretch in Ventura and Santa Barbara counties, and across the Golden Gate Bridge. The highway is designated as an All-American Road. In addition to providing a scenic route to numerous attractions along the coast, the route also serves as a major thoroughfare in the Greater Los Angeles Area, the San Francisco Bay Area, and several other coastal urban areas. SR 1 was built piecemeal in various stages, with the first section opening in the Big Sur region in the 1930s. However, portions of the route had several names and numbers over the years as more segments opened. It was not until the 1964 state highway renumbering that the entire route was officially designated as SR 1. Although SR 1 is a popular route for its scenic beauty, frequent landslides and erosion along the coast have caused several segments to be either closed for lengthy periods for repairs, or re-routed inland. Route description SR 1 is part of the California Freeway and Expressway System, and through the Los Angeles metro area, Monterey, Santa Cruz, and San Francisco metro area is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration. The California State Legislature has also relinquished state control of segments within Dana Point, Newport Beach, Santa Monica, and Oxnard; those segments are now maintained by those respective municipalities. The Big Sur section from San Luis Obispo to Carmel is an official National Scenic Byway. SR 1 is eligible to be included in the State Scenic Highway System; however, only a few stretches between Los Angeles and San Francisco have officially been designated as a scenic highway, meaning that there are substantial sections of highway passing through