As of the census2 of 2000, there were 1,375,765 people, 512,253 households, and 339,623 families residing in the county. The population density was 67/km² (174/mi²). There were 559,799 housing units at an average density of 27/km² (71/mi²). The racial makeup of the county was 71.58% White, 21.96% Hispanic or Latino, 9.08% Black or African American, 5.27% Asian, 0.79% Native American, 0.47% Pacific Islander, 8.61% from other races, and 4.20% from two or more races.

There were 512,253 households out of which 31.70% had children under the age of 18 living with them, 48.70% were married couples living together, 11.80% had a female householder with no husband present, and 33.70% were non-families. 24.50% of all households were made up of individuals and 6.70% had someone living alone who was 65 years of age or older. The average household size was 2.65 and the average family size was 3.17.

In the county the population was spread out with 25.60% under the age of 18, 9.20% from 18 to 24, 32.20% from 25 to 44, 22.30% from 45 to 64, and 10.70% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 103.50 males. For every 100 females age 18 and over, there were 102.80 males.

The median income for a household in the county was $44,616, and the median income for a family was $50,485. Males had a median income of $35,243 versus $27,077 for females. The per capita income for the county was $21,785. 10.80% of the population and 7.90% of families were below the poverty line. 14.10% of those under the age of 18 and 7.30% of those 65 and older were living below the poverty line.