Source:http://linkedlifedata.com/resource/umls/id/C0012764
MSH: A federal area located between Maryland and Virginia on the Potomac river; it is coextensive with Washington, D.C., which is the capital of the United States.,NCI: The area in the United States comprised of a 68 square mile area northeast of the Potomac River donated by the state of Maryland. The District of Columbia, also known as D.C., is not a state, nor is it part of any state. It is a "federal district" established by the US Constitution as the seat of government. The district is occupied entirely by the city of Washington. (from SEERS 2004 codeset)