The British surrender that effectively ended major fighting in the American Revolution occurred at Yorktown, Virginia.
The Siege of Yorktown lasted from September 28 to October 19, 1781. American forces commanded by George Washington and French forces commanded by the Comte de Rochambeau trapped British troops under General Charles Cornwallis. French naval support helped prevent Cornwallis from escaping by sea.
Cornwallis surrendered to the allied army on October 19. The military victory did not instantly create a peace treaty, but it made continued British offensive operations politically and financially difficult. The Treaty of Paris, signed in 1783, formally ended the war and recognized United States independence.
Yorktown is therefore a key event in the longer story commemorated by America250. Saratoga was another major American victory and helped secure French support, while Valley Forge was a winter encampment rather than a decisive battle.