Adams County is the fifth-most populous of the 64 counties of the U.S. state of Colorado. As of the 2010 census, the population was 441,603. The county seat is Brighton. The county is named for Alva Adams, an early Governor of the State of Colorado in 1887–1889.
According to the U.S. Census Bureau, the county has a total area of 1,184 square miles (3,070 km), of which 1,168 square miles (3,030 km) is land and 16 square miles (41 km) (1.4%) is water.
Adams County surrounds (and surrendered the land for) most of Denver International Airport which is in the City and County of Denver.
As of the census of 2000, there were 363,857 people, 128,156 households, and 92,144 families residing in the county. The population density was 305 people per square mile (118/km²). There were 132,594 housing units at an average density of 111 per square mile (43/km²). The racial makeup of the county was 77.29% White, 2.97% Black or African American, 1.19% Native American, 3.21% Asian, 0.12% Pacific Islander, 11.73% from other races, and 3.49% from two or more races. 28.19% of the population were Hispanic or Latino of any race.
There were 128,156 households out of which 37.80% had children under the age of 18 living with them, 53.80% were married couples living together, 12.10% had a female householder with no husband present, and 28.10% were non-families. 21.20% of all households were made up of individuals and 5.50% had someone living alone who was 65 years of age or older. The average household size was 2.81 and the average family size was 3.27.
In the county, the population was spread out with 28.60% under the age of 18, 10.30% from 18 to 24, 34.00% from 25 to 44, 19.40% from 45 to 64, and 7.80% who were 65 years of age or older. The median age was 31 years. For every 100 females there were 102.80 males. For every 100 females age 18 and over, there were 102.10 males.
The median income for a household in the county was $47,323, and the median income for a family was $52,517. Males had a median income of $36,499 versus $28,053 for females. The per capita income for the county was $19,944. About 6.50% of families and 8.90% of the population were below the poverty line, including 10.90% of those under age 18 and 7.30% of those age 65 or over.
In 2000, the largest denominational groups were Catholics (with 60,429 members) and Evangelical Protestants (with 25,552 members). The largest religious bodies were the Catholic Church (with 60,429 adherents) and The Church of Jesus Christ of Latter-day Saints (with 6,808 adherents).