Originally Alexandria County, D.C. formed the portion of the District west of the Potomac, ceded by the commonwealth of Virginia. Alexandria County, including the City of Alexandria, was returned to Virginia by Congress in 1846, leaving just Washington County. Within Washington County there were two incorporated areas, the City of Washington and the City of Georgetown. At times the rural parts outside of the cities were referred to as "Washington County" but all three were part of the county. Upon the passage of the District of Columbia Organic Act of 1871, the three governments were unified under a single District government and made coterminous, ending Washington County's separate identity.