From http://en.wikipedia.org/wiki/Pacific_Coast_Highway_(California) :
Highway 1 is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System. However, only a few stretches between Los Angeles and San Francisco have officially been designated as a scenic highway. The Big Sur section from San Luis Obispo to Carmel is an official National Scenic Byway.
The entire route is also designated as a Blue Star Memorial Highway to recognize those in the United States armed forces. In Southern California, the California Legislature has designated the segment between Interstate 5 (I-5) in Dana Point and US 101 near Oxnard as the Pacific Coast Highway (commonly referred to as “PCH”). Between U.S. 101 at the Las Cruces junction (8 miles south of Buellton) and U.S. 101 in Pismo Beach, and between U.S. 101 in San Luis Obispo and Interstate 280 in San Francisco, the legislature has designated State Highway 1 as the Cabrillo Highway, after Portuguese explorer Juan Rodríguez Cabrillo. The legislature has also designated the route as the Shoreline Highway between the Manzanita Junction near Marin City and Leggett. Smaller segments of the highway have been assigned several other names by the state and municipal governments.
In addition to connecting the coastal cities and communities along its path, Highway 1 also provides access to numerous beaches, parks, and other attractions along the coast, making it a popular route for tourists. The route runs right besides the coastline, or close to it, for the most part, but it also turns several miles inland to avoid several federally-controlled or protected areas such as Vandenberg Air Force Base, Diablo Canyon Power Plant and Point Reyes National Seashore.
Central Coast and Big Sur
Big Sur coastline. Bixby Creek Bridge near the outcropping of rocks which resembles a dinosaur, June, 1965
Looking south showing the McWay Rocks island group, about 16 miles south of Big Sur
The US 101/Highway 1 concurrency (although actual signage mentioning Highway 1 through this segment is nonexistent) from the Mobil Pier Undercrossing runs for 54 miles (87 km), passing through the City of Santa Barbara and its neighboring communities along the coast of Santa Barbara County. Afterwards, Highway 1, now named Cabrillo Highway, splits again from US 101 north of the Gaviota Tunnel, and heads to the coastal city of Lompoc. It is briefly joined with Highway 246 along Lompoc’s east-west Ocean Avenue, before turning north as H Street to Harris Grade Road, where it then regains the Cabrillo Highway name.
After reaching Vandenberg Air Force Base, Highway 1 turns inland, northeast, to join Highway 135. Route 135 then splits from Route 1 south of Orcutt, and the Cabrillo Highway turns northwest back towards the coast to Guadalupe. It then enters San Luis Obispo County, passing through Grover Beach before joining US 101 for the third time at Pismo Beach.
Highway 1 then splits from US 101 at San Luis Obispo and resumes as the Cabrillo Highway. It runs through Morro Bay as a freeway, where it crosses Morro Creek at the site of a prehistoric Chumash settlement dating to the Millingstone Horizon. From there, Highway 1 proceeds north to Cayucos until it again becomes a winding, two lane road with occasional passing lanes. It then continues along the coast through San Simeon and past the elephant seal colony at Piedras Blancas Light.
Highway 1 then enters the Big Sur region, crossing the San Carpoforo Creek just south of the Monterey County line. For about 90 miles (140 km) from the San Carpoforo Creek to the Carmel River, the road winds and hugs the cliffs of Big Sur, passing various coastal parks in the area. This segment of the highway, built between 1919 and 1937, also crosses several historic bridges, including the scenic Bixby Creek Bridge, a reinforced concrete arch with a 320-foot (98 m) span that passes over the Bixby Creek gorge, and the Rocky Creek Bridge.
After crossing the Carmel River, Highway 1 runs along just outside the eastern boundary of Carmel before becoming a freeway in Monterey. The freeway then heads north along the coast of Monterey Bay through Sand City, Seaside, and Marina. At the interchange with Highway 156 near Castroville, Highway 1 continues north as a two-lane rural road to Moss Landing.
Highway 1 becomes a freeway once again just before entering into Santa Cruz County. This four-lane freeway continues up the Monterey Bay through Watsonville to its interchange with Highway 17 in Santa Cruz (the Highway 1/17 interchange is locally known as The Fishhook due to its tight loop ramps that resemble a fishhook when viewed from above). Upon reaching downtown Santa Cruz, it continues as Mission Street and Coast Road, before regaining the Cabrillo Highway name after it leaves the city and continues north as a two lane road up the coast.