- Apr 2 1st Italian Parliament meets at Turin
- Apr 6 Joseph Smith III, creates the Reorganized Church of Jesus Christ of Latter Day Saints by reorganizing the previous church organized by his father, Joseph Smith, Jr.
- Apr 7 Grand duke Frederik I liberalizes laws in Bathe
- Apr 9 Édouard-Léon Scott de Martinville uses his phonautograph to make a 10-second recording of "Au Clair de la Lune"
- Apr 13 1st Pony Express reaches Sacramento, California
- Apr 14 1st Pony Express rider arrives in San Francisco from St Joseph, Missouri
Apr 17 Champion of England Tom Sayers and American John Heenan fight out brutal 2 hour, 27 minute draw near Farnborough, England; police stop fight acknowledged as first world title bout
- Apr 23 Democratic convention in Charleston, South Carolina divided over slavery
- Apr 30 Navaho indians attack Fort Defiance (Canby)