| January 1 | British government demands Falkland islands |
| January 1 | Curaeao census: 2,602 whites, 6,531 free people and 5,894 slaves |
| January 3 | Britain seizes control of Falkland Islands in South Atlantic |
| January 8 | Boston Academy of Music, 1st U.S. music school, established |
| January 10 | Felix Mendelssohn's "Die erste Walpurgisnacht," premieres in Berlin |
| January 15 | HMS Beagle anchors at Goeree Tierra del Fuego |
| January 19 | Charles Darwin reaches Straits Ponsonby, Fireland |
| January 23 | Joseph Pease, a Quaker, admitted to Parliament on his affirmation |
| January 26 | Gaetano Dinozetti's opera "Lucrezia Borgia," premieres in Milan |
| March 16 | Susan Hayhurst becomes 1st U.S. woman grad of a pharmacy college |
| March 17 | Phoenix Society forms (New York) |
| March 20 | U.S. and Siam sign commercial treaty |
| April 9 | 1st tax-supported public library in Peterborough, New Hampshire |
| April 24 | Jacob Evert and George Dulty patent soda fountain |
| April 24 | Patent granted for 1st soda fountain |
| May 2 | Czar Nicolas bans public sale of serfs |
| May 6 | John Deere makes 1st steel plow |
| May 11 | "Lady-of-the-Lake" strikes iceberg and sinks in N Atlantic; kills 215 |
| June 3 | 4th national black convention meets in Philadelphia |
| June 5 | Ada Lovelace (future 1st computer programmer) meets Charles Babbage |
| June 27 | Prudence Crandall, a white woman, arrested for conducting an academy for black females at Canterbury Conn |
| July 8 | Russia and Turkey sign defense treaty |
| July 24 | HMS Beagle departs Maldonado Uruguay |
| August 3 | HMS Beagle reaches river mouth of Rio Negro |
| August 10 | Chicago incorporates as a village of about 200 |
| August 23 | Britain abolishes slavery in colonies; 700,000 slaves freed |
| August 24 | HMS Beagle reaches Bahia Blanca, Argentina |
| September 3 | NY Sun begins publishing (1st daily newspaper) |
| September 4 | 1st newsboy hired (Barney Flaherty, 10 years old-NY Sun) |
| September 8 | Charles Darwin departs to Buenos Aires |
| September 19 | Charles Darwin visits Guardia del Monte, Argentina |
| September 20 | Charles Darwin rides horse to Buenos Aires |
| September 27 | Charles Darwin rides horse to Santa Fe |
| October 1 | Charles Darwin reaches Rio Tercero Argentina |
| October 2 | Charles Darwin rides through Corunda to Santa Fe Argentina |
| October 2 | New York Anti-Slavery Society organized |
| October 3 | Composer Hector Berlioz marries actress Harriet Smithson |
| October 5 | Charles Darwin moves with Parana to Santa Fe Bajada Argentina |
| October 12 | Charles Darwin begins return trip to Buenos Aires |
| October 20 | Charles Darwin reaches river mouth of Parana |
| October 29 | 1st U.S. college fraternity to have a fraternity house founded |
| November 8 | Train derails at Hightstown NJ; 2 die |
| November 14 | Charles Darwin departs by horse to Montevideo |
| November 18 | Netherlands and Belgium sign Treaty of Zonhoven |
| November 20 | Charles Darwin reaches Punta Gorda, sees Rio Uruguay |
| November 28 | Charles Darwin rides through Las Pietras, returning to Montevideo |
| December 3 | Oberlin College in Oh, 1st truly coeducational college opens |
| December 4 | American Anti-Slavery Society formed by Arthur Tappan in Philadelphia |
| December 6 | HMS Beagle/Charles Darwin departs Rio de la Plata |
| December 13 | HMS Beagle/Charles Darwin arrives in Port Deseado, Patagonie |
| December 25 | Charles Darwins celebrates Christmas in Port Desire, Patagonia |
