By train
The COASTER (http://www.gonctd.com/coa...) 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 (http://www.gonctd.com/spr...) rail line runs east-west between Oceanside and Escondido. In San Diego, the San Diego Trolley (http://www.sdmts.com/Trol...) 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.
By bus
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.
By car
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.