Final answer:
Maryland and Virginia initially ceded land for Washington D.C. following the Residence Act of 1790, but the Virginia portion was later returned to the state in 1846.
Step-by-step explanation:
The two states that seceded land for Washington D.C. were Maryland and Virginia. The Residence Act of 1790 authorized the President to select a location for the capital along the Potomac River, and the land was officially ceded by both states shortly thereafter. However, the portion of the land that had been donated by Virginia was retroceded back to the state in 1846. As a result, the District of Columbia is now entirely situated within the borders of Maryland.