Context: Washington, D.C., is located in the mid-Atlantic region of the U.S. East Coast. Due to the District of Columbia retrocession, the city has a total area of 68.34 square miles (177.0 km), of which 61.05 square miles (158.1 km) is land and 7.29 square miles (18.9 km) (10.67 %) is water. The District is bordered by Montgomery County, Maryland, to the northwest; Prince George's County, Maryland, to the east; and Arlington and Alexandria, Virginia, to the south and west.

Question: where's washington dc located on a map?
Steam of consciousness below:
The relevant sentence in the passage is: Washington, D.C., is located in the mid-Atlantic region of the U.S. East Coast.
So, the answer is the mid-Atlantic region of the U.S. East Coast.