District of Columbia retrocession

The District of Columbia retrocession was the act of returning to Virginia some of the land from the District of Columbia that Virginia had previously ceded to the federal government of the United States. The land was originally ceded to the federal government by Virginia and Maryland in 1790 for the purpose of creating a federal district for the new national capital; the capital was moved from Philadelphia to what was then called the City of Washington in 1800.

Source: Wikipedia — District of Columbia retrocession (CC BY-SA 4.0)