Darnestown is a United States census-designated place (CDP) and an unincorporated area in Montgomery County, Maryland. The CDP is 17.70 square miles (45.8 km2) with the Potomac River as its southern border and the Muddy Branch as much of its eastern border. Seneca Creek borders portions of its north and west sides. The Travilah, North Potomac, and Germantown census-designated places are adjacent to it, as is the city of Gaithersburg. Land area for the CDP is 16.39 square miles (42.4 km2). As of the 2020 census, the Darnestown CDP had a population of 6,723, while the village of Darnestown is considerably smaller in size and population. Downtown Washington, D.C. is about 22 miles (35 km) to the southeast.

Germantown is an urbanized census-designated place in Montgomery County, Maryland. With a population of 91,249 as of the 2020 census, it is the third most populous place in Maryland, after Baltimore and Columbia. Germantown is located approximately 28 miles (45 km) outside the U.S. capital of Washington, D.C., and is an important part of the Washington metropolitan area.