San Diego County
San Diego County is the southwestern-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.
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 that are bilingual in English and Spanish, and some people will be bilingual in English and Tagalog (mostly 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.
There are two commercial airports in San Diego County: San Diego International Airport (IATA: SAN) is by far the major one, served by many airlines offering flights from cities around the country and some international flights to Mexico and Canada. McClellan-Palomar Airport (IATA: CLD) in Carlsbad serves a couple of commuter airlines providing service from Los Angeles and Phoenix.
Amtrak's frequent Pacific Surfliner  San Luis Obisbo-Los Angeles-San Diego route serves San Diego County with four stops: one in Oceanside, one in Solana Beach, one at the southern end of the line at Union Station in Downtown San Diego, and a secondary station in Old Town San Diego which is served on weekends.
Three major interstate roadways, I-5, I-8, and I-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.