As of the census of 2000, there were 42,471 people, 12,992 households, and 10,341 families residing in the city. The population density was 3,039.4 people per square mile (1,173.8/km²). There were 13,150 housing units at an average density of 941.1/sq mi (363.4/km²). The racial makeup of the city was 52.22% White, 4.01% Black or African American, 0.64% Native American, 21.30% Asian, 1.00% Pacific Islander, 13.75% from other races, and 7.07% from two or more races. 28.60% of the population were Hispanic or Latino of any race.
There were 12,992 households out of which 40.2% had children under the age of 18 living with them, 62.2% were married couples living together, 11.6% had a female householder with no husband present, and 20.4% were non-families. 14.1% of all households were made up of individuals and 4.2% had someone living alone who was 65 years of age or older. The average household size was 3.26 and the average family size was 3.59.
In the city the population was spread out with 27.3% under the age of 18, 9.5% from 18 to 24, 34.3% from 25 to 44, 21.2% from 45 to 64, and 7.8% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 101.4 males. For every 100 females age 18 and over, there were 99.2 males.
The median income for a household in the city was $69,350, and the median income for a family was $71,351 (these figures had risen to $78,367 and $81,652 respectively as of a 2007 estimate). Males had a median income of $46,061 versus $34,959 for females. The per capita income for the city was $23,641. About 4.2% of families and 5.5% of the population were below the poverty line, including 5.7% of those under age 18 and 6.9% of those age 65 or over.
Newark lies near the intersection of I-880, State Route 84, and the Dumbarton Bridge.
Newark is served by AC Transit bus system. Surrounding Fremont is the access point for most transportation services, including Fremont and Union City BART stations, and ACE and AMTRAK trains.