San Diego County is the southern-most region of Southern California. It encompasses the city of San Diego and its large metropolitan area, which includes many smaller cities and communities. San Diego County lies along the U.S.-Mexican border, across from the Mexican city of Tijuana.
The central, largest city of the county, San Diego sprawls across the southwestern portion of the county and is the focal point for visitors to the area. There's much to explore here; among the most notable attractions are the lush Balboa Park with its museums and famed zoo, sunny beach neighborhoods, the upscale seaside community of La Jolla with its cliffs and scenic coves, the historic district of Old Town, California's oldest Spanish mission, and the thriving urban and nightlife center of Downtown.
East of San Diego lies a mountainous region of high desert that's strikingly rural for its proximity to such a large city. Out here visitors will find desert scenery, arid backcountry, forested towns, charming small towns, several casinos operated by local Indian tribes scattered throughout the area, and wine growing regions like the town of Julian.
To the north of San Diego, this is a mostly suburban region of the county with some notable attractions, including a set of delightful beach towns.
Surrounding the San Diego Bay to the south of San Diego, this is a very built-up region with few major attractions, although you'll find some pleasant beaches and the very busy border crossing of San Ysidro.
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Besides San Diego, there are many smaller cities in the county. Listed here are the major ones:
San Diego County covers a very large area (4,526 square miles, to be exact) with incredibly varied topography. The western half of the county is mostly urbanized, and includes the city of San Diego and its many suburbs to the south, east, and north. The climate of the western half is more moderate, due to its proximity to the ocean, giving San Diego its signature weather. The eastern half is mostly uninhabited or rural, contains snow-capped mountains, forests, and barren desert, and is prone to more extreme weather.
Like much of California, English and Spanish are the dominant languages in San Diego County. Typically, most businesses have at least a few employees who are bilingual in English and Spanish, and some people will be bilingual in English and Tagalog (mostly spoken by San Diego's large Filipino population). It is also common to see store signs printed in both English and Spanish, especially in neighborhoods with large Hispanic populations.
For detailed information on getting in to San Diego, see the Get in section of San Diego.
San Diego International Airport (IATA: SAN) is the only commercial airport in the county and is served by all major U.S. airlines, offering flights from cities around the country and some international flights to Mexico and Canada. General aviation pilots have several airports spread across the region to choose from.
Amtrak's frequent Pacific Surfliner San Luis Obispo-Los Angeles-San Diego route serves San Diego County with several stops along the coast, stopping in Oceanside, Solana Beach, and at the southern end of the line at Union Station in Downtown San Diego, with a secondary station in Old Town San Diego.
Three major interstate roadways, Interstate 5, Interstate 8, and Interstate 15, lead into San Diego County. I-5 runs from the north along the coast, I-8 comes in from the east through the desert, and I-15 leads in to San Diego from the northeast.
In the western half of the region, a complex system of interstate highways and major roads connect the cities and neighborhoods of that half of the region. In the more rural Inland region, only I-8 and a small network of state and county roads run across the area.
The COASTER commuter rail system runs along the coast of San Diego County north of Downtown San Diego, linking together most of the coastal cities and towns of North San Diego County with Old Town and Downtown San Diego. Amtrak's Pacific Surfliner runs this same route, stopping in Oceanside, Solana Beach, and San Diego, but is less practical for getting around the county than the COASTER due to its high price.
In North County, the SPRINTER rail line runs east-west between Oceanside and Escondido. In San Diego, the San Diego Trolley light rail system links several cities east and south of San Diego to the metropolitan center, running east through La Mesa and El Cajon to Santee and south through Chula Vista to the USA-Mexico border.
The Metropolitan Transit System (MTS) and the North County Transit District (NCTD) operate public transit bus services in San Diego County. MTS serves San Diego and many of the surrounding cities, while NCTD serves North County. Service in the Inland region is pretty scarce.
Primary administrative division