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San Diego County, California

County in California, United States

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San Diego County is the southwesternmost county in the 48 contiguous United States, and is a border county. It is home to 18 Indian reservations, the most of any county in the U.S. There are 16 military installations of the United States Navy, Marine Corps, and Coast Guard in the county.

San Diego County comprises the San Diego–Chula Vista–Carlsbad, CA Metropolitan Statistical Area, which is the 18th most populous metropolitan statistical area and the 18th most populous primary statistical area in the U.S. San Diego County is also part of the San Diego–Tijuana region, the largest metropolitan area shared between the U.S. and Mexico. From north to south, San Diego County extends from the southern borders of Orange and Riverside counties to the Mexico–U.S. border and the municipalities of Tijuana and Tecate in Baja California. From west to east, San Diego County stretches from the Pacific Ocean to its boundary with Imperial County, which separated from it in 1907.

San Diego County has more than 70 miles (113 km) of coastline. This forms the most densely populated region of the county, which has a mild Mediterranean to semiarid climate and extensive chaparral vegetation, similar to the rest of the western portion of Southern California. Precipitation and temperature extremes increase to the east, with mountains that receive frost and snow in the winter. These lushly forested mountains receive more rainfall than the average in Southern California, while the desert region of the county lies in a rain shadow to the east, which extends into the Desert Southwest region of North America.

History

The area which is now San Diego County has been inhabited for more than 12,000 years by the Kumeyaay (also known as 'Iipai-Tiipai or by the historical Spanish name Diegueño), Luiseño (also known as Payómkawichum or "People of the West"), Cupeño, Cahuilla, and the Acjachemen people and their local predecessors.

In 1542, the explorer Juan Rodríguez Cabrillo, who may have been born in Portugal but sailed under the flag of Castile, claimed San Diego Bay for the Spanish Empire, and he named the site San Miguel. In November 1602, Sebastián Vizcaíno surveyed the harbor and what are now Mission Bay and Point Loma and named the area for Saint Didacus, a Spaniard more commonly known as San Diego. European settlement in what is now San Diego County began with the founding of the San Diego Presidio and Mission San Diego de Alcalá by Spanish soldiers and clerics in 1769. This county was part of Alta California under the Viceroyalty of New Spain until the Mexican declaration of independence. From 1821 through 1848, this area was part of Mexico.

San Diego County became part of the United States as a result of the Treaty of Guadalupe Hidalgo in 1848, ending the Mexican–American War. This treaty designated the border to pass through a point one marine league south of the southernmost point of the port of San Diego, ensuring that the United States received all of the natural harbor of San Diego Bay.

San Diego County was one of the original counties of California, created at the time of California statehood in 1850.

At the time of its establishment in 1850, San Diego County was relatively large, and included all of southernmost California south and east of Los Angeles County. It included areas of what are now Inyo and San Bernardino Counties, as well as all of what are now Riverside and Imperial Counties.

During the later part of the 19th century, there were numerous changes in the boundaries of San Diego County, when various areas were separated to make up the counties mentioned above. The most recent changes were the establishments of Riverside County in 1893 and Imperial County in 1907. Imperial County was also the last county to be established in California, and after this division, San Diego no longer extended from the Pacific Ocean to the Colorado River, and it no longer covered the entire border between California and Mexico.

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