Sister cities of San Diego

San Diego /ˌsæn diːˈeɪɡoʊ/ is a major city in California, on the coast of the Pacific Ocean in Southern California, approximately 120 miles (190 km) south of Los Angeles and immediately adjacent to the border with Mexico. San Diego is the eighth largest city in the United States and second largest in California and is one of the fastest growing cities in the nation. San Diego is the birthplace of California and is known for its mild year-round climate, natural deep-water harbor, extensive beaches, long association with the U.S. Navy, and recent emergence as a healthcare and biotechnology development center. The population was estimated to be 1,322,553 as of 2012.

Historically home to the Kumeyaay people, San Diego was the first site visited by Europeans on what is now the West Coast of the United States. Upon landing in San Diego Bay in 1542, Juan Cabrillo claimed the entire area for Spain, forming the basis for the settlement of Alta California 200 years later. The Presidio and Mission of San Diego, founded in 1769, formed the first European settlement in what is now California. In 1821, San Diego became part of newly independent Mexico, and in 1850, became part of the United States following the Mexican-American War and the admission of California to the union.

The city is the seat of San Diego County and is the economic center of the region as well as the San Diego–Tijuana metropolitan area. San Diego's main economic engines are military and defense-related activities, tourism, international trade, and manufacturing. The presence of the University of California, San Diego (UCSD), with the affiliated UCSD Medical Center, has helped make the area a center of research in biotechnology.