If Congress wants residents of D.C. as it exists to enjoy full representation, it can initiate the process of amending the Constitution to make it a state. But statehood would be a problem, for the contiguous states, Maryland and Virginia, and for the nation.
The new state probably would promptly enact a commuter tax hitting Maryland and Virginia residents. And, more important, the splendid vistas of the nation's capital might be jeopardized. They are protected by the limits on building heights that Congress mandates. But Congress would have no authority to impose such mandates on the new state. Congress admitted Oklahoma to statehood on the condition that Guthrie remain the state's capital until 1913. But in 1910 Oklahoma made Oklahoma City the capital, and the U.S Supreme Court held that statehood could not be conditioned by limiting a state's sovereign powers. Anyway, 38 state legislatures are unlikely to make of D.C. the only state with no rural interests, and one dominated by a single interest -- the federal government.
Meanwhile, Congress should ponder Judge Karen LeCraft Henderson's recent dissent when a federal appeals court ruled 2-1 that D.C.'s severe restriction on gun ownership violates the Second Amendment. She noted that the Second Amendment restricts the power only of Congress and the states, and she demonstrated that "there is no dispute that the Constitution, case law and applicable statutes all establish that the District is not a state within the meaning of the Second Amendment."
Neither is it a state within the meaning of Article I, Section 2. The Supreme Court will remind Congress of that, if Congress ever sends to a Democratic president, who would sign it, what today's Congress wants to send to President Bush, who surely would veto it. The Constitution's 23rd Amendment, enacted in 1961, entitles D.C. to the number of presidential electoral votes to which it would be entitled "if it were a state." Until it is one, calling it one by statute cannot generate for it the political entitlements "of the several states."