Article 1, Section 8 of the Constitution provides for a federal district (distinct from the states) to serve as the seat of government.
The location of the federal district was a result of a compromise between Hamilton, Madison, and Jefferson. The U.S. capital city was New York at the time. Jefferson didn't want the federal government controlled by one of the largest Northern states. So he struck a bargain with Hamilton, agreeing to support Hamilton's plan for the federal government to assume the states' debts in exchange for the creation of a federal district apart from the power of any one of the states of the union (and further south).
I understand the history, but it hardly seems relevant to the current situation. Having the seat of federal power exist in a state-less region makes sense, but having half a million people live there too doesn't.
And why no Senators? It's not like DC would be the least populous state, yet I don't see many campaigns to strip Wyoming of its senators.
Seems like most of the opposition is from Republicans who recognize that DC would almost certainly elect liberal Democrats. And that's just ridiculously unfair.
I think the bigger problem is that we let people make permanent residence in area that was designed not to be part of a state. Perhaps they could shrink the DC area down and give the residential land back to the appropriate states.
The location of the federal district was a result of a compromise between Hamilton, Madison, and Jefferson. The U.S. capital city was New York at the time. Jefferson didn't want the federal government controlled by one of the largest Northern states. So he struck a bargain with Hamilton, agreeing to support Hamilton's plan for the federal government to assume the states' debts in exchange for the creation of a federal district apart from the power of any one of the states of the union (and further south).
You can read more about the reasons for removing the capital from state territory here: http://en.wikipedia.org/wiki/Residence_Act
(Full disclosure: I wouldn't mind Eleanor Holmes Norton getting a vote in the House, but I would be against DC having senators.)