As of the census of 2000, there were 1,682,585 people, 565,863 households, and 395,538 families residing in the county. The population density was 1,304 people per square mile (503/km²). There were 579,329 housing units at an average density of 449 per square mile (173/km²). The racial makeup of the county was 53.83% White, 2.80% Black or African American, 0.67% Native American, 25.56% Asian, 0.34% Pacific Islander, 12.13% from other races, and 4.66% from two or more races. 23.98% of the population were Hispanic or Latino of any race. 6.7% were of German and 5.4% English ancestry according to Census 2000. 54.7% spoke English, 17.6% Spanish, 5.7% Vietnamese, 5.3% Chinese or Mandarin, 3.3% Tagalog and 1.2% Korean as their first language.
There were 565,863 households out of which 34.90% had children under the age of 18 living with them, 54.90% were married couples living together, 10.00% had a female householder with no husband present, and 30.10% were non-families. 21.40% of all households were made up of individuals and 5.90% had someone living alone who was 65 years of age or older. The average household size was 2.92 and the average family size was 3.41.
In the county the population was spread out with 24.70% under the age of 18, 9.30% from 18 to 24, 35.40% from 25 to 44, 21.00% from 45 to 64, and 9.50% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 102.80 males. For every 100 females age 18 and over, there were 101.90 males.
The median income for a household in the county was $74,335, and the median income for a family was $81,717. Males had a median income of $56,240 versus $40,574 for females. The per capita income for the county was $32,795. About 4.90% of families and 7.50% of the population were below the poverty line, including 8.40% of those under age 18 and 6.40% of those age 65 or over.
Santa Clara County has the highest median household income of any county in California.
The county has an extensive freeway system (now nearing completion) and a separate expressway system. Expressways in California are distinct from freeways; although access to adjoining properties is eliminated, at-grade intersections are allowed. However, unlike expressways virtually everywhere else in California, the Santa Clara County expressways were built, signed, and maintained as county roads; they are not maintained by Caltrans, although they are patrolled by the California Highway Patrol.
There is also a large street network dominated by four- and six-lane arterials. Some of the newer boulevards (primarily in the West Valley) are divided with landscaped medians.
Santa Clara County has consolidated its transportation services into the Santa Clara Valley Transportation Authority, which operates a rapidly expanding light rail system and a large system of bus routes. It also manages certain county-funded highway and expressway projects.
Besides SCVTA, the County is also served by Caltrain commuter rail service, and the ACE Train system, which runs between San Jose and Stockton.
The county's main airport is Norman Y. Mineta San José International Airport (SJC). Moffett Federal Airfield (NUQ), a former Naval Air Station, is used by the Air National Guard, NASA, Lockheed Martin, and Google. There are also smaller general aviation airports in Palo Alto (PAO), San Jose (RHV), and San Martin (E16).
The county has no commercial seaports, although small boats can access San Francisco Bay from several points. Like many other Bay Area counties, it is dependent upon the Port of Oakland for transport of ocean cargo.