Potomac is a census-designated place (CDP) in Montgomery County, Maryland, United States, named for the nearby Potomac River. The population was 44,822 at the 2000 census. The Potomac area is known for its very affluent and highly-educated residents. In 2009 CNNMoney. com listed Potomac as the fourth most affluent town in the United States. Potomac is also the seventh most top-educated American small town according to Forbes. Many Potomac residents work in Washington, D.C.