Williamson is a census-designated place (CDP) in Yavapai County, Arizona, United States. The population was 3,776 at the 2000 census. The name “Wiliamson” is a misnomer, perhaps propagated by federal bureaucratic error; the area has long been known as “Williamson Valley” after the major road through the area, Williamson Valley Road.
Williamson is located at 34°40′28″N 112°31′50″W / 34.67444°N 112.53056°W / 34.67444; -112.53056 (34.674552, -112.530445).
According to the United States Census Bureau, the CDP has a total area of 57.6 square miles (149 km), all of it land.
An attempt in 2009 to incorporate the area into a town failed after the neighboring town of Prescott voted against the proposal.
As of the census of 2000, there were 3,776 people, 1,558 households, and 1,266 families residing in the CDP. The population density was 65.5 people per square mile (25.3/km²). There were 1,718 housing units at an average density of 29.8/sq mi (11.5/km²). The racial makeup of the CDP was 96.90% White, 0.11% Black or African American, 0.40% Native American, 0.29% Asian, 0.11% Pacific Islander, 0.79% from other races, and 1.40% from two or more races. 3.52% of the population were Hispanic or Latino of any race.
There were 1,558 households out of which 20.9% had children under the age of 18 living with them, 74.8% were married couples living together, 4.4% had a female householder with no husband present, and 18.7% were non-families. 14.2% of all households were made up of individuals and 5.1% had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 2.65.
In the CDP, the population was spread out with 17.7% under the age of 18, 3.8% from 18 to 24, 17.1% from 25 to 44, 41.3% from 45 to 64, and 20.1% who were 65 years of age or older. The median age was 51 years. For every 100 females, there were 96.8 males. For every 100 females age 18 and over, there were 95.8 males.
The median income for a household in the CDP was $47,182, and the median income for a family was $51,983. Males had a median income of $40,189 versus $26,500 for females. The per capita income for the CDP was $30,232. About 3.6% of families and 5.3% of the population were below the poverty line, including 7.1% of those under age 18 and 1.5% of those age 65 or over.