The District of Columbia Organic Act of 1871 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 1861.
In 1846 Alexandria County was returned by Congress to the state of Virginia. 
The District of Columbia Organic Act of 1871 is an Act of Congress that repealed the individual charters of the cities of Washington and Georgetown and established a new territorial government for the whole District of Columbia. 
