As of the census of 2000, there were 174,682 people, 59,556 households, and 42,939 families residing in the county. The population density was 46 people per square mile (18/km²). There were 65,210 housing units at an average density of 17 per square mile (7/km²). The racial makeup of the county was 67.82% White, 1.56% Black or African American, 1.48% Native American, 0.76% Asian, 0.07% Pacific Islander, 24.74% from other races, and 3.58% from two or more races. 63.35% of the population were Hispanic or Latino of any race.
There were 59,556 households out of which 38.40% had children under the age of 18 living with them, 52.40% were married couples living together, 14.70% had a female householder with no husband present, and 27.90% were non-families. 21.30% of all households were made up of individuals and 6.90% had someone living alone who was 65 years of age or older. The average household size was 2.85 and the average family size was 3.36.
In the county the population was spread out with 29.70% under the age of 18, 13.30% from 18 to 24, 27.10% from 25 to 44, 19.30% from 45 to 64, and 10.60% who were 65 years of age or older. The median age was 30 years. For every 100 females there were 96.50 males. For every 100 females age 18 and over, there were 93.50 males.
The median income for a household in the county was $29,808, and the median income for a family was $33,576. Males had a median income of $27,215 versus $20,883 for females. The per capita income for the county was $13,999. 25.40% of the population and 20.20% of families were below the poverty line. Out of the total people living in poverty, 34.40% are under the age of 18 and 12.70% are 65 or older.