Missouri Compromise — legislative compromise between pro- and anti-slavery parties in the run-up to the American Civil War

1820 battle between the Zulu and Ndwandwe tribes

1820 United States presidential election — 9th quadrennial U.S. presidential election

1820 treaty of Argentina

1820s — decade of the Gregorian calendar

Battle between Portuguese and Oriental forces in Tacuarembó, Banda Oriental

1820 treaty between France and the Netherlands

1820 treaty between the United States and Choctaw

1820 battle of the Ecuadorian War of Independence

1820 battle of the Ecuadorian War of Independence