A terri-tory situated on the Potomac river, and being the seat of government of the United States. It was originally ten miles square, and was composed of portions of Maryland and Virginia ceded by those states to the United States; but in 1846 the tract coming from Virginia was retroceded. Legally lt is nel-ther a state nor a territory, but is made sub-Ject, by the constitution, to the exclusive Ju-risdictlon of congress