Arapahoe County is a county located in the U.S. state of Colorado . As of 2000, the population is 487,967. The county seat is Littleton ; the largest city is Aurora . According to the U.S. Census Bureau, the county has a total area of 2,086 km² (805 mi²). 2,080 km² (803 mi²) of it is land and 6 km² (2 mi²) of it is water. The total area is 0.28% water.

As of the census2 of 2000, there are 487,967 people, 190,909 households, and 125,809 families residing in the county. The population density is 235/km² (608/mi²). There are 196,835 housing units at an average density of 95/km² (245/mi²). The racial makeup of the county is 79.93% White, 7.67% Black or African American, 0.66% Native American, 3.95% Asian, 0.12% Pacific Islander, 4.51% from other races, and 3.16% from two or more races. 11.81% of the population are Hispanic or Latino of any race.

The median income for a household in the county is $53,570, and the median income for a family is $63,875. Males have a median income of $41,601 versus $31,612 for females. The per capita income for the county is $28,147. 5.80% of the population and 4.20% of families are below the poverty line. Out of the total population, 7.00% of those under the age of 18 and 5.10% of those 65 and older are living below the poverty line.

Neighboring areas include: Adams County , Washington County, Lincoln County ; Elbert County , Douglas County , Jefferson County , and Denver city & county .