Other adjacent federal facilities include the National Archives at College Park and headquarters of the Food and Drug Administration. The following is a list of historic sites in Adelphi identified by the Maryland-National Capital Park and Planning Commission: Adelphi is located at (38.996860, −76.966755). According to the United States Census Bureau, the Census Designated Place (CDP) has a total area of , all land. As of 2000, there were 14,998 people, 5,332 households, and 3,321 families that were reported to be living in Adelphi, Maryland. The population density was 5,067.9 people per square mile (1,956.3/km²). There were 5,627 housing units at an average density of 1,901.4/sq mi (734.0/km²). The racial makeup of the CDP was quite diverse, including 29.48% White, 39.83% African American, 0.28% Native American, 9.95% Asian, 0.06% Pacific Islander, 15.04% from other races, and 5.36% from two or more races. Hispanic or Latino of any race were 25.74% of the population. There were 5,332 households out of which 30.6% had children under the age of 18 living with them, 42.5% were married couples living together, 13.5% had a female householder with no husband present, and 37.7% were non-families. 27.5% of all households were made up of individuals and 6.1% had someone living alone who was 65 years of age or older. The average household size was 2.77 and the average family size was 3.35. In the CDP, the age distribution of the population included 22.7% under the age of 18, 13.0% from 18 to 24, 35.7% from 25 to 44, 19.1% from 45 to 64, and 9.5% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 98.1 males. For every 100 females age 18 and over, there were 96.6 males. The median income for a household in the CDP was $45,827, and the median income for a family was $53,839. Males had a median income of $32,495 versus $31,932 for females.