December 3 - Gregor MacGregor, Scottish con-man (b. 1786)
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.