Events from the year 1781 in the United States. This year marked the beginning of government under the Articles of Confederation as well as the surrender of British armed forces in the American Revolution.
June 3 – American Revolution – Jack Jouett begins a "midnight ride" to warn Thomas Jefferson and the Virginia legislature of approaching British cavalry led by Banastre Tarleton who have been sent to capture them
July 29 – American Revolution – Skirmish at the House in the Horseshoe: A Tory force under David Fanning attacks Phillip Alston's smaller force of Whigs at Alston's home in Cumberland County, North Carolina (in present-day Moore County, North Carolina). Alston's troops surrender after Fanning's men attempt to ram the house with a cart of burning straw.
August 19 – Congress passes an act saying they will recognize the secessionist state of Vermont (formed in 1777 by unilateral separation from New York) and agree to admit that state to the Union if Vermont will renounce its claims to territory east of the Connecticut River and west of Lake Champlain. (The following spring the Vermont legislature agreed, but nonetheless New York continued to block its admission until 1791.)
September 4 – Los Angeles is founded as El Pueblo de Nuestra Señora La Reina de Los Ángeles de Porciuncula (City of Our Lady the Queen of the Angels of Porciuncula) by a group of 44 Spanish settlers.
September 10 – American Revolution: Graves gives up trying to break through the now-reinforced French fleet and returns to New York, leaving Cornwallis to his fate.