1. The Lincoln Assassination: April 15, 1865
- Shortly after the end of the American Civil War, President Abraham Lincoln was shot in the head by John Wilkes Booth while attending a play at Ford's Theater in Washington, D.C.
2. The San Francisco Earthquake: April 18, 1906
- Early in the morning of April 18, 1906, a powerful earthquake, centered on the northern California coast, shook the city of San Francisco.
3. The Sinking of the Titanic: April 15, 1912
- The passenger liner RMS Titanic sank after striking an iceberg on her maiden voyage across the Atlantic.
4. The Ludlow Massacre: April 20, 1914
- a gunfight broke out between the miners and guards, the guards fired on the tent colony with a machine gun. 20 people, including 12 children, were killed.
5. The Hillsborough Disaster: April 15, 1989
- Overcrowding in the standing-only central pen at Hillsborough Stadium in Sheffield, England led to a disastrous event in which 96 people were crushed to death and 766 were injured.
6. The Waco Siege ends: April 19, 1993
- At the end of the standoff, the FBI used tear gas in an attempt to flush the Branch Davidians out of the compound. Shortly after, a massive fire broke out, which resulted in the deaths of 76 people, including children.
7. The Oklahoma City Bombing: April 19, 1995
- A truck loaded with ammonium nitrate fertilizer exploded outside the Alfred P. Murrah federal building in downtown Oklahoma City, killing 168 people.
8. The Columbine High School Massacre: April 20, 1999
- Two students at Columbine High School in Littleton, Colorado shot and killed 12 students and one teacher and wounded an additional 21 people in a massacre that made the word "Columbine" synonymous with school shootings.
9. The Virginia Tech Shooting: April 16, 2007
- Undergraduate student Seung-Hui Cho shot 49 people, killing 32, in the worst school shooting in United States history.
10. The Deepwater Horizon Disaster: April 20, 2010
- The Deepwater Horizon oil drilling rig was destroyed by an explosion and subsequent fire while drilling for BP about 40 miles off the Louisiana coast. 11 workers were killed and 17 others were injured.
11. The Boston Marathon Bombing: April 15, 2013
- Terrorists detonated two bombs near the finish line at the Boston Marathon in 2013, killing three people and injuring more than 250.
12. The West Fertilizer Company Explosion: April 17, 2013
- A fire broke out at a fertilizer storage and distribution facility in the city of West, Texas, about 18 miles north of Waco. As firefighters responded, a massive ammonium nitrate explosion killed 15 people, injured 160 others and destroyed or damaged more than 150 buildings in West.
13. The Notre Dame Cathedral Fire: April 15, 2019
- A fire started in the roof of the famous Notre-Dame de Paris cathedral and spread through the structure, toppling the iconic lead and timber spire as firefighters rushed to save the irreplaceable relics and works of art from the 800-year-old church.