Claim: The District of Columbia Organic Act of 1871, a statute enacted by Congress, allowed the cities of Washington, Alexandria and Georgetown to each maintain their own municipal governments but  Alexandria County was returned by Congress to the state of Virginia in 1846.
Evidence: Though Congress repealed the territorial government in 1874, the legislation was the first to create a single municipal government for the federal district. 
An Act to provide a Government for the District of Columbia.