As of the census of 2000, there were 20,224 people, 7,226 households, and 5,542 families residing in the town. The population density was 639.9 people per square mile (247.0/km²). There were 7,447 housing units at an average density of 235.6/sq mi (91.0/km²). The racial makeup of the town was 93.85% White, 0.47% Black or African American, 0.62% Native American, 1.10% Asian, 0.06% Pacific Islander, 1.86% from other races, and 2.04% from two or more races. 6.18% of the population were Hispanic or Latino of any race.
There were 7,226 households out of which 45.7% had children under the age of 18 living with them, 65.3% were married couples living together, 8.2% had a female householder with no husband present, and 23.3% were non-families. 17.6% of all households were made up of individuals and 3.7% had someone living alone who was 65 years of age or older. The average household size was 2.78 and the average family size was 3.18.
In the town the population was spread out with 31.6% under the age of 18, 6.9% from 18 to 24, 38.2% from 25 to 44, 18.6% from 45 to 64, and 4.7% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 101.0 males. For every 100 females age 18 and over, there were 97.6 males.
The median income for a household in the town was $69,138, and the median income for a family was $72,563 (these figures had risen to $81,136 and 88,811 respectively as of a 2007 estimate). Males had a median income of $47,626 versus $32,328 for females. The per capita income for the town was $26,760. About 2.5% of families and 3.6% of the population were below the poverty line, including 3.2% of those under age 18 and 5.4% of those age 65 or over.