December 3 - Gregor MacGregor, Scottish con-man (b. 1786)
Events
January 1 - The Cobble Hill Tunnel in Brooklyn is completed.
January 29 - "The Raven" by Edgar Allan Poe is published in the New York Evening Mirror.
March 1 - President John Tyler signs a bill authorizing the United States to annex the Republic of Texas.
March 3 - Florida is admitted as the 27th U.S. state.
March 3 - For the first time the U.S. Congress passes legislation overriding a presidential veto.
March 11 - The Flagstaff War: In New Zealand, Chiefs Hone Heke and Kawiti lead 700 Māoris to chop down the British flagpole and drive settlers out of the British colonial settlement of Kororareka because of breaches of the 1840 Treaty of Waitangi.
March 11 - British baker Henry Jones invents self-raising flour.
March 13 - Felix Mendelssohn's Violin Concerto is premièred in Leipzig with Ferdinand David as soloist.
May 20 - HMS Erebus and HMS Terror with 134 men under John Franklin sail from the River Thames in England, beginning a disastrous expedition to find the Northwest Passage. All hands are lost.
July 4 - Near Concord, Massachusetts, Henry David Thoreau embarks on a two-year experiment in simple living at Walden Pond (see Walden).
August 6 - The Russian Geographical Society is founded in Saint Petersburg.
August 28 - Scientific American magazine publishes its first issue.
September 23 - The Knickerbockers Baseball Club, the first baseball team to play under the modern rules, is founded in New York.
October 9 - The eminent and controversial Anglican, John Henry Newman, is received into the Roman Catholic Church.
October 10 - In Annapolis, Maryland, the Naval School (later renamed the United States Naval Academy) opens with 50 midshipmen students and seven professors.
October 13 - A majority of voters in the Republic of Texas approve a proposed constitution, that if accepted by the U.S. Congress, will make Texas a U.S. state.
November 29 - The Sonderbund is defeated by the joint forces of other Swiss cantons under General Guillaume-Henri Dufour.
December 2 - Manifest Destiny: US President James K. Polk announces to Congress that the United States should aggressively expand into the West.
December 6 - Alpha Sigma Phi Fraternity is founded at Yale College.
December 27 - Ether anesthetic is used for childbirth for the first time by Dr. Crawford Williamson Long in Jefferson, Georgia.
December 29 - Texas is admitted as the 28th U.S. state.
