Federal government edit

• President: James Monroe (DR-Virginia)
• Vice President: Daniel D. Tompkins (DR-New York)
• Chief Justice: John Marshall (Virginia)
• Speaker of the House of Representatives: Henry Clay (DR-Kentucky) (until October 28), John W. Taylor (DR-New York) (starting November 15)
• Congress: 16th

• February 6 – 86 free African American colonists sail from New York City to Freetown, Sierra Leone.
• March 3 & 6 – Slavery in the United States: The Missouri Compromise becomes law.
• March 15 – Maine is admitted as the 23rd U.S. state (see History of Maine).
• April 24 – The Land Act of 1820 reduces the price of land in the Northwest Territory and Missouri Territory encouraging Americans to settle in the west.
• August 7 – The 1820 United States Census is conducted, eventually determining a population of 11,176,475.
• December 3 – U.S. presidential election, 1820: James Monroe is re-elected, virtually unopposed.

Undated edit

• Mount Rainier erupts over what is today Seattle.
• Indiana University is founded as the Indiana State Seminary and renamed the Indiana College in 1846, to later be renamed Indiana University.
• Charlottesville Woolen Mills built along the Rivanna River

Ongoing edit

• Era of Good Feelings (1817–1825)

• February 1 – George Hendric Houghton, Episcopal clergyman (died 1897)
• February 4 – David C. Broderick, U.S. Senator from California from 1857 to 1859 (died 1859)
• February 6
  • Henry Howard Brownell, poet and historian (died 1872)
  • Thomas C. Durant, American railroad financier (died 1885)
• February 8 – William Tecumseh Sherman, Civil War general (died 1891)^[1]
• February 15 – Susan B. Anthony, suffragist (died 1906)
• March 1 – George Davis, Confederate States Senator from North Carolina, 4th and last Confederate States Attorney General (died 1896)
• March 3 – Henry D. Cogswell, temperance campaigner and philanthropist (died 1900)
• March 17 – William F. Raynolds, military engineer (died 1894)
• March 24
  • Fanny Crosby, mission worker and hymnist (died 1915)
  • George G. Wright, U.S. Senator from Iowa from 1871 to 1877 (died 1896)
• April 8 – John Taylor Johnston, businessman and patron of the arts (died 1893)
• April 17 – Alexander Cartwright, baseball pioneer (died 1892 in Hawaii)
• April 26 – Alice Cary, poet and short story writer, sister to Phoebe Cary (died 1871)
• May 23 – Lorenzo Sawyer, 9th Chief Justice of the Supreme Court of California (died 1891)
• May 30 – Edward Doane, Protestant missionary (died 1890)
• June 2 – Willard Saulsbury, Sr., U.S. Senator from Delaware from 1859 to 1871 (died 1892)
• July 5 – Luke Pryor, U.S. Senator from Alabama in 1880 (died 1900)
• July 23 – Julia Gardiner Tyler, First Lady of the United States (died 1889)
• July 31 – John W. Garrett, banker, railroad president and philanthropist (died 1884)
• August 26 – James Harlan, U.S. Senator from Iowa from 1865 to 1866 (died 1899)
• August 30 – George Frederick Root, songwriter (died 1895)
• September 2 – Lucretia Peabody Hale, journalist and author (died 1900)^[2]
• September 3 – George Hearst, U.S. Senator from California from 1887 to 1891 (died 1891)
• September 20 – John F. Reynolds, U.S. Army general (killed 1863)
• October 5 – David Wilber, politician (died 1890)
• October 28 – John Henry Hopkins, Jr., Episcopal clergyman and hymnist (died 1891)
• November 13 – Eugene Casserly, U.S. Senator from California from 1869 to 1873 (died 1883)
• December 12 – James L. Pugh, U.S. Senator from Alabama from 1880 to 1897 (died 1907)
• December 19 – Mary Livermore, born Mary Ashton Rice, journalist, abolitionist and women's rights advocate (died 1905)
• December 21 – William H. Osborn, railroad president and philanthropist (died 1894)
• December 29 – John S. Barbour, Jr., U.S. Senator from Virginia from 1889 to 1892 (died 1892)
• Eagle Woman, Lakota leader (died 1888)

• February 5 – William Ellery, signer of the United States Declaration of Independence, Chief Justice of the Rhode Island Supreme Court (born 1729)
• March 11 – Benjamin West, American-born painter of historical scenes (born 1738)
• March 22 – Stephen Decatur, U.S. Navy commander (born 1779)
• April 14 – Levi Lincoln Sr., statesman from Massachusetts (born 1749)
• April 20 – James Morris III, Continental Army officer from Connecticut (born 1752)
• July 10 – William Wyatt Bibb, U.S. Senator from Georgia from 1813 to 1816, 1st Governor of Alabama (born 1781)
• August 12 – Manuel Lisa, fur trader (born 1772)
• September 3 – Benjamin Henry Latrobe, architect (born 1764 in Great Britain)
• September 21 – Joseph Rodman Drake, poet (born 1795; consumption)
• September 26 – Daniel Boone, pioneer (born 1734)
• September 29 – Barthelemy Lafon, Creole architect, engineer, city planner, surveyor and smuggler (born 1769 in France)
• October 4 – Thomas Hope, architect (born 1757 in Great Britain)
• November 8 – Lavinia Stoddard, poet and educationalist (born 1787)

• Timeline of United States history (1820–1859)

• Daniel Blowe (1820). A geographical, historical, commercial, and agricultural view of the United States of America; forming a complete emigrant's directory through every part of the republic ... London: Edwards & Knibb. OL 14686561M.

•   Media related to 1820 in the United States at Wikimedia Commons