The District of Columbia retrocession was the process of returning to the state of Virginia a part of the land that had been ceded to the federal government of the United States for the purpose of creating Washington, D.C., the national capital. The area, formed in 1790 under the name of "District of Columbia",  initially consisted of 100 square miles (259 km 2) ceded by the states of Maryland and Virginia in accordance with the Residence Act.
In 1846, the area of 31 square miles (80 km 2) which was ceded by Virginia was returned,  leaving 69 square miles (179 km 2) of territory originally ceded by Maryland as the current area of the District in its entirety.  21st-century proposals to return the remaining portion of the District of Columbia to the state of Maryland are cited as one way to provide full voting representation in Congress and return local control of the city to its residents. 
The Organic Act of 1801 organized the District of Columbia and placed the federal territory under the exclusive control of Congress. The District was organized into two counties, Washington on the east side of the Potomac River, and Alexandria on the west side.   Following this Act, citizens located in the District were no longer considered residents of Maryland or Virginia, thus ending their representation in Congress. 
Almost immediately after the Organic Act of 1801, Congress took up proposals for the return of the territory to the states, all of which failed. Members of Congress proposed retrocession because they found disenfranchisement of the District's residents to be unacceptable. Other Congressmen were of the opinion that the District could not be immediately returned without the consent of the residents and the legislatures of Maryland and Virginia. Some representatives rejected the idea of retrocession entirely and concluded that the Congress lacked the constitutional authority to return the territory. 
In the 1830s, efforts grew to reunite the southern portion of the District with Virginia. Besides the fact that District residents had lost representation in Congress, a number of additional factors aided the movement to return the area to Virginia:
- Alexandria had gone into economic decline because of neglect of the area by Congress. Alexandria needed infrastructure improvements in order to compete with other ports in the area such as Georgetown, which was further inland and on the Chesapeake and Ohio Canal.  Members of Congress from other areas of Virginia used their power to prohibit funding for projects, such as the Alexandria Canal, which would have increased competition with their home districts. Returning Alexandria to Virginia allowed residents to seek financing for projects without interference from Congress. 
- A 1791 amendment to the Residence Act specifically prohibited the "erection of the public buildings otherwise than on the Maryland side of the river Potomac."  The institutions of the federal government, including the White House and the United States Capitol were therefore located in Washington on the east side of the Potomac River. This made Alexandria less important to the functioning of the national government. 
- At the time, Alexandria was a major market in the American slave trade, but rumors circulated that abolitionists in Congress were attempting to end slavery in the nation's capital, which would have also seriously harmed the area's economy.  
- There was also an active abolitionist movement in Virginia. If Alexandria were returned to the state of Virginia, the move would have added two additional pro-slavery representatives to the Virginia General Assembly. 
From 1840 to 1846, Alexandrians petitioned Congress and the Virginia legislature to approve retrocession. On February 2, 1846, the Virginia General Assembly agreed to accept the retrocession of Alexandria if Congress approved. 
Following additional lobbying by Alexandrians, the 29th Congress passed legislation on July 9, 1846, to return all the District's territory south of the Potomac River to the Commonwealth of Virginia, pursuant to a referendum; President James K. Polk signed the legislation the next day.
A referendum on retrocession was held on September 1–2, 1846. The residents of the city of Alexandria voted in favor of the retrocession, 763 to 222;  however, the residents of Alexandria County voted against retrocession 106 to 29. Despite the objections of those living in Alexandria County, President Polk certified the referendum and issued a proclamation of transfer on September 7, 1846. 
The Virginia legislature, however, did not immediately accept the retrocession offer. Virginia legislators were concerned that the people of Alexandria County had not been properly included in the retrocession proceedings. After months of debate, the Virginia General Assembly voted to formally accept the retrocession legislation on March 13, 1847. 
The Supreme Court of the United States has never issued a firm opinion on whether the retrocession of the Virginia portion of the District of Columbia was constitutional. In the 1875 case of Phillips v. Payne the Supreme Court held that Virginia had de facto jurisdiction over the area returned by Congress in 1847, and dismissed the tax case brought by the plaintiff. The court, however, did not rule on the core constitutional matter of the retrocession. Writing the majority opinion, Justice Noah Haynes Swayne stated only that:
The plaintiff in error is estopped from raising the point which he seeks to have decided. He cannot, under the circumstances, vicariously raise a question, nor force upon the parties to the compact an issue which neither of them desires to make. 
The constitutionality of the retrocession has been called into question. The contract clause found in Article One of the United States Constitution prohibits states from breaching contracts to which they are themselves a party. By annexing Alexandria in 1847, Virginia may have breached its contractual obligation to "forever cede and relinquish" the territory for use as the permanent seat of the United States government.  President William Howard Taft also believed the retrocession to be unconstitutional and tried to have the land given back to the District. 
Proposed Maryland retrocession
In order to grant the residents of the District of Columbia voting representation and control over their local affairs, some members of Congress, such as Rep. Dan Lungren,  have proposed returning most parts of the city to Maryland. These proposals go back at least as far as 1839, when some members of Congress proposed retrocession of the portion of the District west of Rock Creek to Maryland.  In recent years since at least 2001, several failed attempts, mostly supported by Republicans, have been made to return most of the District to Maryland and give them full voting rights: &, both sponsored by Rep. Ralph Regula (R-OH); and,, and, all sponsored by Rep. Louie Gohmert (R-TX). The proposals received little support from congressional Democrats.
If both the Congress and the Maryland state legislature agreed, jurisdiction over the District of Columbia could be returned to Maryland, excluding a small tract of land immediately surrounding the United States Capitol, the White House and the Supreme Court building which would become known as the "National Capital Service Area".  The idea to retrocede all but the federal lands to Maryland dates back to at least 1848. 
One problem with retrocession is that the state of Maryland may not want to take the District back.   In the opinion of former Rep. Tom Davis of Virginia, discussing the matter in 1998, retroceding the District to Maryland without that state's consent may require a constitutional amendment. 
A second problem is that the Twenty-third Amendment, ratified in 1961, grants "[t]he District constituting the seat of Government of the United States" the right to appoint electors to vote for president. At least one bill proposed in Congress specifically tied retrocession to the Twenty-third Amendment's repeal.  If the Twenty-third Amendment were not repealed, it is possible that the remaining portion of the city (the National Capital Service Area) would still be entitled to select three presidential electors.
Alternative to have District residents voting in Maryland
A related, but alternative proposal to retrocession was the District of Columbia Voting Rights Restoration Act of 2004 (H.R. 3709), which would have treated the residents of the District as residents of Maryland for the purposes of Congressional representation. Maryland's congressional delegation would then have been apportioned accordingly to include the population of the District.  Those in favor of such a plan argued that the Congress already has the necessary authority to pass such legislation without the constitutional concerns of other proposed remedies. From the foundation of the District in 1790 until the passage of the Organic Act of 1801, citizens living in D.C. continued to vote for members of Congress in Maryland or Virginia; legal scholars therefore propose that the Congress has the power to restore those voting rights while maintaining the integrity of the federal district.  The proposed legislation, however, never made it out of committee. 
Neither residents of Maryland nor of DC support retrocession. A 1994 study showed that only 25% of suburban residents polled endorsed retrocession to Maryland, and that number dropped to 19% among District residents. District residents’ dislike was confirmed in a 2000 George Washington University study when only 21% of those polled supported the option of retrocession.  A 2016 poll of Maryland residents showed that only 28% supported annexing Washington, DC while 44% were opposed. 
Maryland's senators, both Democrats, are co-sponsors of a September 2014 D.C. statehood bill. Republicans are thought to oppose statehood over retrocession, as it would most likely add two safe Democratic seats to the United States Senate. Neither statehood nor retrocession is generally seen as a legislative priority by either party.