I’d never heard of the federal district court for the District of Potomac until today, but it turns out there was such a court, albeit only briefly, in 1801-02. The District of Potomac included the territory of “Columbia” together with parts of Virginia and Maryland. The new district was set up by Section 21 of the Judiciary Act of 1801:
And a new district shall be established, in the districts of Maryland and Virginia, to consist of the territory of Columbia, of all that part of the district of Maryland, which lies west and southwest of the river Patuxent, and of the western branch thereof, and south of the line which divides the county of Montgomery in the last mentioned district, from the county of Frederick, and of a line to be drawn from the termination of the last mentioned line, a northeast course to the western branch of the Patuxent; and of all that part of the district of Virginia, which lies north of the river Rappahannock, and east of the line which divides the counties of Fauquier and Loudon, in the last mentioned district from the counties of Fairfax, Prince William, and Stafford; which new district shall be called the district of Potomac, and a district court in and for the same, shall be holden at Alexandria, by the district judge of the district of Maryland, on the first Tuesday in April, and the first Tuesday in October, in each and every year.
The District of Potomac didn’t last long, as the Judiciary Act of 1801 was repealed by Congress a year later. I don’t know of any opinions by that court that were published, although there’s a reference to the court in passing in the Reporter’s summary of the procedural history of United States v. Nourse, 31 U.S. 470, 480 (1832) (referring to “[t]he answer of the United States of America, to a bill of injunction filed against them in the district court of the United States for the district of Potomac, by Joseph Nourse, late register of the treasury of the United States.”)