Santa Clara County Library, is a public library system serving the communities and cities of Campbell, Cupertino, Gilroy, Los Altos, Los Altos Hills, Milpitas, Monte Sereno, Morgan Hill, Saratoga, and all unincorporated areas of the county. All other cities run their own library system. The county's main airport is Norman Y. Mineta San José International Airport (SJC). It is a U.S. Customs and Border Protection port of entry and as of 2019 has five international routes (one to Canada, one to England, one to Japan, one to Mexico, and one to China) but the airport's busiest routes are all to cities in the western United States. San Francisco International Airport (SFO) is also often used for commercial services by residents of Santa Clara County. Moffett Federal Airfield (NUQ), a former U.S. Naval Air Station, is used by the Air National Guard, NASA, Lockheed Martin, Google, and by the San Jose Police and Santa Clara County Sheriff's Department as an air operations base. There are also smaller general aviation airports in Palo Alto (PAO), San Jose (Reid-Hillview) (RHV), and San Martin(E16)  Santa Clara County is served by Caltrain commuter rail from Gilroy through San Jose and Silicon Valley north to San Francisco Airport and San Francisco. The Santa Clara Valley Transportation Authority operates the VTA light rail system, which primarily serves San Jose, with one line continuing as far north as Mountain View. Santa Clara and San Jose are also served by the Altamont Corridor Express commuter rail line which provides services to Stockton, and Amtrak which provides service to Sacramento and Oakland. The Amtrak Coast Starlight train between Seattle and Los Angeles also stops in San Jose. BART currently services Milpitas and North San Jose, with plans to extend to downtown San Jose and Santa Clara. Santa Clara County has consolidated its transportation services into the Santa Clara Valley Transportation Authority, which operates a bus system. The Santa Clara Valley Transportation Authority is establishing a bicycle network throughout the county. Santa Clara County Bicycle network is part of the San Francisco Bay Area Regional Bikeway Network. The county has an extensive freeway system and a separate expressway system (though it's not as extensive as those in Southern California). Expressways in California are distinct from freeways; although access to adjoining properties is eliminated, at-grade intersections are allowed. However, unlike expressways virtually everywhere else in California, the Santa Clara County expressways were built, signed, and maintained as county roads; they are not maintained by Caltrans, although they are patrolled by the California Highway Patrol.