Santa Fe County (Spanish: Holy faith) is a county in the U.S. state of New Mexico. As of the 2010 census, the population was 144,170, making it New Mexico's third-most populous county, after Bernalillo County and Doña Ana County. Its county seat is Santa Fe, the state capital.
According to the U.S. Census Bureau, the county has a total area of 1,911 square miles (4,950 km2), of which 1,909 square miles (4,940 km2) is land and 1.5 square miles (3.9 km2) (0.08%) is water. It is the fifth-smallest county in New Mexico by area. The highest point in the county is the summit of Santa Fe Baldy at 3,847 meters (12,621 ft). It is drained by the Rio Grande and several of its small tributaries.
There were 52,482 households out of which 30.4% had children under the age of 18 living with them, 45.5% were married couples living together, 11.7% had a female householder with no husband present, and 37.5% were non-families. 29.4% of all households were made up of individuals and 7.4% 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 3.01.
In the county, the population was spread out with 24.1% under the age of 18, 8.1% from 18 to 24, 29.7% from 25 to 44, 27.3% from 45 to 64, and 10.8% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 95.8 males. For every 100 females age 18 and over, there were 93.4 males.
The median income for a household in the county was $42,207, and the median income for a family was $50,000. Males had a median income of $33,287 versus $27,780 for females. The per capita income for the county was $23,594. About 9.4% of families and 12% of the population were below the poverty line, including 15.2% of those under age 18 and 9.7% of those age 65 or over.