Transportation in California

California's transportation system is complex and dynamic. Although known for its car culture and extensive network of freeways and roads, the state also has a vast array of rail, sea, and air transport. Several subway, light rail, and commuter rail networks are found in many of the state's largest population centers. In addition, with the state's location on the West Coast of the United States, several important ports in California handle freight shipments from the Pacific Rim and beyond. A number of airports are also spread out across the state, ranging from small general aviation airports to large international hubs like Los Angeles International Airport and San Francisco International Airport.

However, in a state with over 37 million people, rapid population expansion, and diverse terrain and weather, that system is under pressure to stay ahead of population growth and transportation needs.

California is known for its car culture; by the end of 2010, the California Department of Motor Vehicles had 23,799,513 driver's licenses and a total of 31,987,821 registered vehicles on file. The state's residents typically take to the roads for their commutes, errands, and vacations, giving California's cities a reputation for severe traffic congestion. California has some of the worst roads in the United States.

California's vast terrain is connected by an extensive system of freeways, expressways, and highways, all maintained by the California Department of Transportation (Caltrans) and patrolled by the California Highway Patrol (CHP), except for the numbered expressways in Santa Clara County which were built and maintained by the county itself. The main north-south arteries are U.S. Route 101 (US 101), which travels close to the coast from Downtown Los Angeles, across the Golden Gate Bridge, and to the Oregon state line, and Interstate 5 (I-5), which travels inland from the Mexico–United States border to the Oregon state line, effectively bisecting the entire state. In addition, a major north-south artery is State Route 99 (SR 99), which travels from near Bakersfield to near Red Bluff; SR 99 is largely parallel to I-5, and connects the Central Valley cities not connected by the Interstate.

...
Wikipedia