February 6 - The first minstrel show in the United States The Virginia Minstrels opens (Bowery Amphitheatre in New York City).
February 11 - Giuseppe Verdi's opera I Lombardi receives its first performance in Milan.
May 16 - The first major wagon train heading for the Pacific Northwest sets out on the Oregon Trail with one thousand pioneers from Elm Grove, Missouri.
May 22 - Thousands of people and their cattle head west via wagon train from Independence, Missouri to what would later become the Oregon Territory. It is part of the Great Migration. They follow what is now known as the Oregon Trail.
July 19 - Brunel's steamship the SS Great Britain is launched, becoming the first ocean-going craft with an iron hull or screw propeller and also becoming the largest vessel afloat in the world.
August 15 - The Cathedral of Our Lady of Peace in Honolulu, Hawaii is dedicated. Now the cathedral of the Roman Catholic Diocese of Honolulu, it is the oldest Roman Catholic cathedral in continuous use in the United States.
August 15 - Tivoli Gardens, one of the oldest still intact amusement parks in the world, opens in Copenhagen, Denmark.
October 1 - The News of the World tabloid began publication in London.
October 13 - In New York City, Henry Jones and 11 others found B'nai B'rith (the oldest Jewish service organization in the world).
October 14 - The British arrest Irish nationalist Daniel O'Connell for conspiracy.
October 16 - Sir William Rowan Hamilton comes up with the idea of quaternions, a non-commutative extension of complex numbers.