San Diego's economy is largely composed of agriculture, biotechnology/biosciences, computer sciences, electronics manufacturing, defense-related manufacturing, financial and business services, ship-repair and construction, software development, telecommunications, and tourism. The presence of the University of California, San Diego (UCSD) with the affiliated UCSD Medical Center promotes research in biotechnology.
As of the census of 2000, there were 1,223,400 people, 450,691 households, and 271,315 families residing in the city. The population density was 3,771.9 people per square mile (1,456.4/km²).
There were 451,126 households out of which 30.2% had children under the age of 18 living with them, 44.6% were married couples living together, 11.4% had a female householder with no husband present, and 39.8% were non-families. 28.0% of all households were made up of individuals and 7.4% had someone living alone who was 65 years of age or older. The average household size was 2.61 and the average family size was 3.30.
In the city the population was spread out with 24.0% under the age of 18, 12.4% from 18 to 24, 34.0% from 25 to 44, 19.1% from 45 to 64, and 10.5% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 101.7 males. For every 100 females age 18 and over, there were 100.4 males.
Population by race/ethnicity (Census 2000 def.):
According to estimates by the San Diego Association of Governments, as of January 1, 2008, the population of San Diego rose to 1,336,865, up 9.3% from 2000. The population was 45.3% non-Hispanic White, 27.7% Hispanic, 15.6% Asian/Pacific Islander, 7.1% Black, 0.4% American Indian, 3.9% of other races. Median age of Hispanics was 27.5 years, compared to 35.1 years overall and 41.6 years among non-Hispanic Whites; Hispanics were the largest group in all ages under 18, and non-Hispanic Whites constituted 63.1% of population 55 and older.
San Diego had a declining crime rate from 1990 to 2000, which slightly increased in the early 2000s. In 2004, San Diego had the sixth lowest crime rate of any U.S. city with over half a million residents. From 2002 to 2006, violent crime decreased 12.4% while overall crime decreased only 0.8% partly due to a 1.1% increase in property crime. Total property crimes were lower than the national average in 2004.
With the automobile being the primary means of transportation for over 80% of its residents, San Diego is served by an extensive network of freeways and highways. This includes Interstate 5, which runs south to Tijuana and runs north to the Canadian border through Orange County, Los Angeles, Sacramento, Portland, and Seattle; I-8, which runs east to Imperial County and Arizona; I-15, which runs north to the Canadian border through Riverside County and Salt Lake City; and I-805, which splits from I-5 at Sorrento Valley and rejoins I-5 near the Mexican border. Notable state highways are SR 94, which connects downtown with I-805, I-15 and east county; SR 163, which connects downtown with the northeast part of the city, intersects I-805 and merges with I-15 at Miramar; SR 52, which connects La Jolla with east county through Santee and SR 125; SR 56, which connects I-5 with I-15 through Carmel Valley and Rancho Peñasquitos; and SR 75 (San Diego-Coronado Bridge), which spans San Diego Bay.
Several regional transportation projects have been undertaken in recent years to deal with congestion on San Diego freeways. This includes expansion of Interstates 5 and 805 around "The Merge," a rush-hour spot where the two freeways meet. Also, an expansion of Interstate 15 through the North County is underway with the addition of high-occupancy-vehicle (HOV) "managed lanes". There is a tollway (The South Bay Expressway) connecting SR 54 and Otay Mesa, near the Mexican border. According to a 2007 assessment, 37% of streets in San Diego were in acceptable driving condition. The proposed budget fell $84.6 million short of bringing the city's streets to an acceptable level.
San Diego is served by the trolley, bus, Coaster, and Amtrak. The trolley (system map) primarily serves downtown and surrounding urban communities, Mission Valley, east county, and coastal south bay. A planned Mid-Coast line will operate from Old Town to University City along the 5 Freeway. There are also plans for a Silver Line to expand trolley service downtown.
The Amtrak and Coaster trains currently run along the coastline and connect San Diego with Los Angeles, Orange County, Riverside, San Bernardino, and Ventura via Metrolink. There are two Amtrak stations in San Diego, in Old Town, and Union Station (downtown).
The bus is available along almost all major routes; however, a large number of bus stops are concentrated in central San Diego. Typical wait times vary from 15 to 30 minutes, depending on the location and route. Trolleys arrive at each station every 7 to 30 minutes (depending on time of day and which trolley line is used). Ferries are also available every half hour crossing San Diego Bay to Coronado.
San Diego's roadway system provides an extensive network of routes for travel by bicycle. The dry and mild climate of San Diego makes cycling a convenient and pleasant year-round option. At the same time, the city's hilly, canyoned terrain and significantly long average trip distances—brought about by strict low-density zoning laws—somewhat restrict cycling for utilitarian purposes. Older and denser neighborhoods around the downtown tend to be friendlier to utility cycling. This is partly because of the grid street patterns now absent in newer developments farther from the urban core, where suburban style arterial roads are much more common. As a result, a vast majority of cycling-related activities are recreational. The city has some segregated cycle facilities, particularly in newer developments although the majority of road facilities specifically for bicycles are painted on regular roadways. In 2006, San Diego was rated as the best city for cycling for U.S. cities with a population over 1 million.
San Diego International Airport, also known as Lindbergh International Airport or Lindbergh Field, is the primary commercial airport serving San Diego. It is the busiest single-runway airport in the United States, serving over 17 million passengers every year, and is located on San Diego Bay three miles (4.8 km) from downtown. There are scheduled flights to the rest of the United States, Mexico, Hawaii, and Canada. It serves as a focus city or "hub" for Southwest Airlines. Other airports include Brown Field Municipal Airport (Brown Field) and Montgomery Field. Aeroméxico provides a shuttle service from San Diego to General Abelardo L. Rodríguez International Airport in Tijuana, Baja California, Mexico.
There has been debate regarding the placement of a new international airport. While the San Diego Airport Authority has endorsed the current site of the Miramar Marine Corps Air Station, the military said it has no intention of relinquishing that site. A vote on the issue took place on November 7, 2006 against Proposition A, in which voters rejected the proposal to move the airport to Miramar. The military has rejected the proposals for a dual-use airport because the area around Miramar has already been set aside as safety corridors for military aircraft accidents. A shared commercial/military airport would force military aircraft to fly outside of those safety corridors.
The Port of San Diego manages the maritime operations of San Diego harbor. Cruise ships arrive and depart from San Diego's cruise ship terminal on B Street Pier. Carnival Cruise Lines, Royal Caribbean, Holland America, and Celebrity Cruises have home port cruise ships in San Diego during the winter season. A new cruise terminal on Broadway Pier is set to open in 2010.
San Diego is home to General Dynamics' National Steel and Shipbuilding Company (NASSCO), the largest shipyard on the West Coast of the United States. It is capable of building and repairing large ocean-going vessels. The yard constructs commercial cargo ships and auxiliary vessels for the U.S. Navy and Military Sealift Command, which it has served since 1960.