The following important events in the history of the District of Columbia affected political boundaries, record keeping, and family movements.
- 1788-1791: Maryland ceded parts of Montgomery (including Georgetown) and Prince George counties to the United States, and Virginia ceded part of Fairfax County (including the town of Alexandria). Those counties continued to govern the area until about 1801, but Virginia kept permanent custody of the records for Alexandria.
- 1790: Act of 16 July 1790 organized territory of the District.
- 1800: Congress, the President, and a staff of about 140 people moved from Philadelphia to Washington.
- 1801: Two counties were established in the District: Washington County, east of the Potomac, and Alexandria County, on the west side of the river. The City of Washington was incorporated in 1802. Georgetown wills and deeds continued to be registered in Montgomery County, Maryland, until the late nineteenth century.
- 1814: During the War of 1812, the British captured Washington and burned most of the public buildings and records.
- 1861-1865: Although defended by federal troops during the Civil War, Washington was several times threatened by Confederates. The civilian population of Washington more than doubled during the 1860s.
- 1871: Congress changed the city's status to that of a federal territory.
- 1878: Present-day form of government started.
- 1898: Over 300,000 men were involved in the Spanish-American War which was fought mainly in Cuba and the Philippines.
- 1917–1918: More than 26 million men from the United States ages 18 through 45 registered with the Selective Service. World War I over 4.7 million American men and women served during the war.
- 1930's: The Great Depression closed many factories and mills. Many small farms were abandoned, and many families moved to cities.
- 1940–1945: Over 50.6 million men ages 18 to 65 registered with the Selective Service. Over 16.3 million American men and women served in the armed forces during World War II.
- 1950–1953: Over 5.7 million American men and women served in the Korean War.
- 1950's–1960's: The building of interstate highways made it easier for people to move long distances.
- 1964–1972: Over 8.7 million American men and women served in the Vietnam War.
A good history of the District of Columbia is John Clagett Proctor, E. Melvin Williams, and Frank P. Black Washington, Past and Present, 4 vols. New York City: Lewis Historical Publ., 1930. 975.3/W1 H2p.