Federal government edit

• President: Martin Van Buren (D-New York)
• Vice President: Richard M. Johnson (D-Kentucky)
• Chief Justice: Roger B. Taney (Maryland)
• Speaker of the House of Representatives: Robert Mercer Taliaferro Hunter (W-Virginia)
• Congress: 26th

• January 13–14 – The steamship Lexington burns and sinks in icy waters, 4 miles off the coast of Long Island; 139 die, only 4 survive.
• January 19 – Captain Charles Wilkes circumnavigates Antarctica, claiming what becomes known as Wilkes Land for the United States.
• March 4 – Alexander S. Wolcott and John Johnson open their "Daguerreian Parlor" on Broadway (Manhattan), the world's first commercial photography portrait studio.
• March 9 – The Wilmington and Raleigh Railroad is completed from Wilmington, North Carolina to Weldon, North Carolina. At 161.5 miles, it was the world's longest railroad at the time.^[1]
• April – The Raleigh and Gaston Railroad is completed from Raleigh, North Carolina to near Weldon, North Carolina.^[2]
• May 7 – The Great Natchez Tornado: A massive tornado strikes Natchez, Mississippi during the early afternoon hours. Before it is over, 317 people are killed and 109 injured. It is the second deadliest tornado in U.S. history.
• November 7 – U.S. presidential election, 1840: William Henry Harrison defeats Martin Van Buren.

Ongoing edit

• Second Seminole War (1835–1842)

• January 1 – Patrick Walsh, Irish-born U.S. Senator from Georgia from 1894 to 1895 (died 1899)
• January 29 – Henry H. Rogers, financier (died 1909)
• February 4 – Hiram Stevens Maxim, firearms inventor (died 1916)
• February 9 – William T. Sampson, U.S. Navy admiral (died 1902)
• March 5 – Constance Fenimore Woolson, fiction writer and poet (died 1894)
• April 28 – Caroline Shawk Brooks, sculptor (died 1913)
• May 1 – Cynthia S. Burnett, educator, temperance reformer, and newspaper editor (died 1932)
• May 4 – George Gray, U.S. Senator from Delaware from 1885 to 1899 (died 1925)
• June 3 – Michael O'Laughlen, conspirator in the assassination of Abraham Lincoln in 1865 (died 1867)
• June 6 – William Dudley Chipley, railroad tycoon and statesman (died 1897)
• June 14 – William F. Nast, attaché, railroad executive and inventor (died 1893)
• June 27 – Alpheus Beede Stickney, railroad executive (died 1916)
• July 10 – Esther G. Frame, Quaker minister and evangelist (died 1920)
• July 21 – Christian Abraham Fleetwood, Union Army 4th Colored Infantry Regiment soldier and Medal of Honor recipient (died 1914)
• August 25 – George C. Magoun, railroad executive (died 1893)
• August 28 – Ira D. Sankey, gospel singer and composer (died 1908)
• September 10 – William B. Avery, Union Army soldier and Medal of Honor recipient (died 1894)
• September 22 – D. M. Canright, Seventh-day Adventist minister and author, later one of the church's severest critics (died 1919)
• September 27 – Alfred Thayer Mahan, U.S. Navy admiral, geostrategist and historian (died 1914)
• September 23 – Simon B. Conover, U.S. Senator from Florida from 1873 to 1879 (died 1908)
• October 1 – Anthony Higgins, U.S. Senator from Delaware from 1889 to 1895 (died 1912)
• October 24 – Eliza Pollock, American archer (died 1919)
• November 24 – John Brashear, astronomer (died 1920)
• Earliest probable date – Crazy Horse (Tȟašúŋke Witkó), Chief of the Oglala Lakota (killed 1877)

• March 11 – George Wolf, politician (born 1777)
• March 23 – William Maclure, geologist (born 1763 in Scotland; died in Mexico)
• April 7 – Thaddeus Betts, U.S. Senator from Connecticut from 1839 to 1840 (born 1789)
• August 10 – Seymour Brunson, early Mormon convert (born 1798)
• August 27 – William Kneass, second Chief Engraver of the United States Mint from 1824 to 1840 (born 1781)
• September 14 – Joseph Smith Sr., 1st Presiding Patriarch of the Latter Day Saint movement (born 1771)
• September 18 – Constantine Samuel Rafinesque, French polymath (born 1783 in the Ottoman Empire)
• June 14 – Anson Brown, lawyer and U.S. Representative from New York from 1839 to 1840 (born 1800)

• Timeline of United States history (1820–1859)

•   Media related to 1840 in the United States at Wikimedia Commons