As an unincorporated area, Bethesda has no official boundaries, but various areas are considered to constitute Bethesda. The United States Census Bureau defines a Census-Designated Place named Bethesda whose center is located at 38°59' North, 77°7' West. The United States Geological Survey has defined Bethesda as an area whose center is at 38°58'50" North, 77°6'2" West, slightly different from the Census Bureau's definition. Other definitions are used by the Bethesda Urban Planning District and other organizations. As of the 2000 census, the community had a total population of 55,277.
The important institutions located there include the U.S. National Institutes of Health and the U.S. National Imagery and Mapping Agency.
Bethseda also has the headquarters of Lockheed Corporation.
Bethesda is located at 38°59'5" North, 77°6'47" West (38.984660, -77.113135)1.
According to the United States Census Bureau, the CDP has a total area of 34.2 km² (13.2 mi²). 34.0 km² (13.1 mi²) of it is land and 0.1 km² (0.1 mi²) of it is water. The total area is 0.38% water.
As of the census of 2000, there are 55,277 people, 23,659 households, and 14,455 families residing in the defined area. The population density is 1,624.2/km² (4,205.8/mi²). There are 24,368 housing units at an average density of 716.0/km² (1,854.1/mi²). The racial makeup of the community is 85.86% White, 2.67% African American, 0.17% Native American, 7.92% Asian, 0.05% Pacific Islander, 1.23% from other races, and 2.11% from two or more races. 5.43% of the population are Hispanic or Latino of any race.
There are 23,659 households out of which 28.0% have children under the age of 18 living with them, 53.4% are married couples living together, 6.0% have a female householder with no husband present, and 38.9% are non-families. 32.2% of all households are made up of individuals and 11.6% have someone living alone who is 65 years of age or older. The average household size is 2.30 and the average family size is 2.92.
In the community the population is spread out with 21.9% under the age of 18, 4.6% from 18 to 24, 29.2% from 25 to 44, 27.1% from 45 to 64, and 17.2% who are 65 years of age or older. The median age is 41 years. For every 100 females there are 87.7 males. For every 100 females age 18 and over, there are 84.0 males.
The median income for a household in the area is $99,102, and the median income for a family is $130,160. Males have a median income of $84,797 versus $57,569 for females. The per capita income for the area is $58,479. 3.3% of the population and 1.7% of families are below the poverty line. Out of the total people living in poverty, 1.8% are under the age of 18 and 4.1% are 65 or older.