District of Columbia Organic Act of 1801

The District of Columbia Organic Act of 1801 (officially An Act Concerning the District of Columbia) (6th Congress, 2nd Sess., ch. 15, 2 Stat. 103, enacted 1801-02-27) is an Organic Act enacted by the United States Congress in accordance with Article 1, Section 8 of the United States Constitution. It formally placed the District of Columbia under the control of the United States Congress and organized the unincorporated territory within the District into two counties: Washington County to the north and east of the Potomac River and Alexandria County to the west and south. The charters of the existing cities of Georgetown and Alexandria were left in place and no change was made to their status. The common law of both Maryland and Virginia remained in force within the District. A court was established in each of the new counties.

On May 3, 1802, the City of Washington was granted a municipal government consisting of a mayor appointed by the President of the United States. The portion of the District of Columbia ceded by Virginia was returned to that state in 1846-47. The District of Columbia Organic Act of 1871 replaced the municipal governments of the City of Washington, Georgetown, and Washington County with a single, unified government for the whole District.

...
Wikipedia