Beginning with the attacks of September 11, 2001, the 21st century has seen a marked rise in the threat of terrorism. Since 1970, more than 3,900 people have been killed by terrorist attacks in the United States, and data from the National Consortium for the Study of Terrorism and Responses to Terrorism, or START, shows that 88% of those fatalities occurred since the year 2000.
While nearly a quarter century has passed since the events of 9/11, terrorism remains a leading threat to American national security. In its 2025 Homeland Threat Assessment report, the U.S. Department of Homeland Security stated that the terrorism threat environment remains high, due to a number of social, political, and ideological factors, as well as international developments. These include U.S. election cycles, grievances toward specific racial, religious, or gender identity groups, and the conflict between Israel and Hamas. Potential perpetrators include domestic violent extremists as well as foreign terrorist organizations, and the homegrown violent extremists they inspire.
Terrorism is a dynamic threat, and despite the vast resources devoted by the DHS and FBI to protecting American citizens, some attacks — particularly those carried out by lone individuals — still elude federal law enforcement each year.
Using data from START, a joint project between the Department of Homeland Security and the University of Maryland, 24/7 Wall St. identified the deadliest terror attacks in the United States. Rankings are based on the total number of fatalities for each of the approximately 2,900 terrorist attacks carried out on American soil between 1970 and 2021, as reported in the START Global Terrorism Database. Only incidents that resulted in at least 10 deaths appear on this list. All supplemental data are also sourced from the GTD.
To be considered a terrorist act by START, an incident must have been intentional, carried out by a non-state actor, and involve violence or the threat of violence. Additionally, to be counted, an incident must meet at least two of the following criteria: it is aimed at attaining a political, religious, social, or economic reform goal; it is intended to send a message to a broader audience than the immediate victims; or it occurs outside the context of legitimate warfare. Notably, this list includes some incidents where it is unclear whether all of these criteria were fully met.
With the exception of the events of Sept. 11, 2001, the terrorist attacks on this list were geographically isolated. For the purposes of this story, the lives lost on 9/11 are grouped into one of three discrete events — the collapse of the Twin Towers in New York City, the assault on the Pentagon, and the crash of the hijacked passenger aircraft in Shanksville, Pennsylvania.
Among the 18 terrorist attacks on this list, total death tolls range from 10 to nearly 2,800. In most cases, all or nearly all reported fatalities were American citizens. Cumulatively, these attacks also wounded nearly 23,850 people, most of whom were Americans. The groups that carried out these attacks include foreign terrorist organizations, anti-government extremists, Neo-Nazis, white supremacists, and anti-Semitic extremists. Most of these events are classified as armed assaults, but other methods of violence employed by the perpetrators include hijacking, hostage taking, and bombing.
These are the deadliest terrorist attacks in the United States.
Why It Matters
Although more than two decades have passed since the events of September 11, 2001, the terrorist threat to the United States remains dynamic and elevated, with attacks carried out by individuals acting alone becoming increasingly common. While the events of September 11 stand as the single deadliest terror attack in U.S. history, terrorism was a constant threat decades before 9/11 and remains so today.
18. Umpqua Community College Shooting
- Total number of fatalities: 10 (100% American citizens)
- Number of non-fatally wounded: 7 (100% American citizens)
- Date of incident: Oct 1, 2015
- Attack type: Hostage taking (barricade incident)
- Attack location: Umpqua Community College; Roseburg, Oregon
- Targeted entity: Educational institution
- Perpetrator group: Incel extremists
- Weapons used in attack: .56 caliber Del-Ton DTI15 semi-automatic rifle, .40 caliber Smith & Wesson Model 99 pistol, .38 caliber Smith & Wesson Model M642-2 pistol, .380 caliber HiPoint pistol, .40 caliber Taurus Model T24 pistol, 9 mm Glock Model 19 pistol
- Level of property damage: Minor (likely less than $1 million)
17. Santa Fe High School Shooting
- Total number of fatalities: 10 (100% American citizens)
- Number of non-fatally wounded: 14 (100% American citizens)
- Date of incident: May 18, 2018
- Attack type: Armed assault
- Attack location: Santa Fe High School; Santa Fe, Texas
- Targeted entity: Educational institution
- Perpetrator group: Neo-Nazi extremists
- Weapons used in attack: .38 caliber revolver, shotgun, two inoperable explosive devices
- Level of property damage: Minor (likely less than $1 million)
16. Dayton Shooting
- Total number of fatalities: 10 (100% American citizens)
- Number of non-fatally wounded: 27 (100% American citizens)
- Date of incident: August 4, 2019
- Attack type: Armed assault
- Attack location: Ned Peppers Bar; Dayton, Ohio
- Targeted entity: Business
- Perpetrator group: Unknown
- Weapons used in attack: AM-15 .223-caliber semi-automatic rifle
- Level of property damage: Minor (likely less than $1 million)
15. Pittsburgh Synagogue Shooting
- Total number of fatalities: 11 (100% American citizens)
- Number of non-fatally wounded: 7 (100% American citizens)
- Date of incident: Oct. 27, 2018
- Attack type: Armed assault
- Attack location: Tree of Life Synagogue, Pittsburgh Bureau of Police; Pittsburgh, Pennsylvania
- Targeted entity: Religious figures/institutions and law enforcement
- Perpetrator group: Anti-Semitic extremists
- Weapons used in attack: Colt AR-15 semi-automatic rifle, three Glock .357 caliber semi-automatic handguns
- Level of property damage: Unknown
14. LaGuardia Airport Bombing
- Total number of fatalities: 11
- Number of non-fatally wounded: 74
- Date of incident: Dec. 29, 1975
- Attack type: Bombing/explosion
- Attack location: LaGuardia Airport; New York City, New York
- Targeted entity: Airports and aircraft
- Perpetrator group: Croatian nationalists
- Weapons used in attack: Explosives
- Level of property damage: Minor (likely less than $1 million)
13. Fort Hood Shooting
- Total number of fatalities: 13 (100% American citizens)
- Number of non-fatally wounded: 32 (100% American citizens)
- Date of incident: Nov. 5, 2009
- Attack type: Armed assault
- Attack location: Fort Hood Army Base; Killeen, Texas
- Targeted entity: Military personnel
- Perpetrator group: Jihadi-inspired extremists
- Weapons used in attack: Two semi-automatic pistols
- Level of property damage: Unknown
12. Columbine High School Massacre
- Total number of fatalities: 15 (100% American citizens)
- Number of non-fatally wounded: 24 (100% American citizens)
- Date of incident: April 20, 1999
- Attack type: Hostage taking (kidnapping), armed assault
- Attack location: Columbine High School; Littleton, Colorado
- Targeted entity: Educational institution, private citizens
- Perpetrator group: Unknown
- Weapons used in attack: Multiple firearms, Molotov cocktails, knives, pipe bombs, and other explosive devices
- Level of property damage: Unknown
11. West Fertilizer Company explosion
- Total number of fatalities: 15 (100% American citizens)
- Number of non-fatally wounded: 151 (100% American citizens)
- Date of incident: April 17, 2013
- Attack type: Facility/infrastructure attack
- Attack location: West Fertilizer Company; West, Texas
- Targeted entity: Business
- Perpetrator group: Unknown
- Weapons used in attack: Incendiary device
- Level of property damage: Unknown
10. San Bernardino Attack
- Total number of fatalities: 16 (93.8% American citizens)
- Number of non-fatally wounded: 17 (93.8% American citizens)
- Date of incident: Dec. 2, 2015
- Attack type: Bombing/explosion, armed assault
- Attack location: Department of Public Health; San Bernardino, California
- Targeted entity: Government
- Perpetrator group: Jihadi-inspired extremists
- Weapons used in attack: Remote-controlled explosive device containing three pipe bombs, .223 AR-15 semiautomatic rifles, 9mm semiautomatic pistols
- Level of property damage: Unknown
9. Parkland High School Shooting
- Total number of fatalities: 17 (100% American citizens)
- Number of non-fatally wounded: 17 (100% American citizens)
- Date of incident: Feb. 14, 2018
- Attack type: Armed assault
- Attack location: Stoneman Douglas High School; Parkland, Florida
- Targeted entity: Educational institution
- Perpetrator group: White supremacists/nationalists
- Weapons used in attack: Smith & Wesson M&P15 semi-automatic rifle
- Level of property damage: Unknown
8. El Paso Walmart Shooting
- Total number of fatalities: 23 (60.9% American citizens)
- Number of non-fatally wounded: 24 (60.9% American citizens)
- Date of incident: August 3, 2019
- Attack type: Armed assault
- Attack location: Walmart; El Paso, Texas
- Targeted entity: Business
- Perpetrator group: White supremacists/nationalists
- Weapons used in attack: WASR-10 semi-automatic rifle
- Level of property damage: Minor (likely less than $1 million)
7. Luby’s Massacre
- Total number of fatalities: 24 (100% American citizens)
- Number of non-fatally wounded: 27 (100% American citizens)
- Date of incident: Oct. 16, 1991
- Attack type: Armed assault
- Attack location: Luby’s Cafeteria; Killeen, Texas
- Targeted entity: Business
- Perpetrator group: Male supremacists
- Weapons used in attack: Glock 17 and Ruger P89 9mm handguns
- Level of property damage: Minor (likely less than $1 million)
6. 9/11 Hijacked Aircraft Crash
- Total number of fatalities: 44 (86.4% American citizens)
- Number of non-fatally wounded: 9 (86.4% American citizens)
- Date of incident: Sept. 11, 2001
- Attack type: Hijacking, armed assault
- Attack location: Shanksville, Pennsylvania
- Targeted entity: Private citizens and property
- Perpetrator group: Al-Qaida
- Weapons used in attack: Knives, passenger aircraft, jet fuel
- Level of property damage: Catastrophic (likely more than $1 billion)
5. Pulse Nightclub Shooting
- Total number of fatalities: 50 (88.0% American citizens)
- Number of non-fatally wounded: 53 (88.0% American citizens)
- Date of incident: June 12, 2016
- Attack type: Hostage taking (barricade incident), armed assault
- Attack location: Pulse Nightclub; Orlando, Florida
- Targeted entity: Business
- Perpetrator group: Jihadi-inspired extremists
- Weapons used in attack: Sig Sauer MCX assault rifle, Glock 17 handgun
- Level of property damage: Minor (likely less than $1 million)
4. Las Vegas Mass Shooting
- Total number of fatalities: 60 (93.3% American citizens)
- Number of non-fatally wounded: 850 (93.3% American citizens)
- Date of incident: Oct. 1, 2017
- Attack type: Armed assault
- Attack location: Mandalay Bay Resort and Casino, McCarran International Airport; Las Vegas, Nevada
- Targeted entity: Business
- Perpetrator group: Anti-government extremists
- Weapons used in attack: AR-15 semiautomatic rifles
- Level of property damage: Unknown
3. Oklahoma City Bombing
- Total number of fatalities: 168 (100% American citizens)
- Number of non-fatally wounded: 650 (100% American citizens)
- Date of incident: April 19, 1995
- Attack type: Bombing/explosion
- Attack location: Alfred P. Murrah Federal Building; Oklahoma City, Oklahoma
- Targeted entity: Government
- Perpetrator group: Anti-government extremists
- Weapons used in attack: Explosives
- Level of property damage: Major (likely more than $1 million but less than $1 billion)
2. 9/11 Terror Attack on the Pentagon
- Total number of fatalities: 190 (95.8% American citizens)
- Number of non-fatally wounded: 106 (95.8% American citizens)
- Date of incident: Sept. 11, 2001
- Attack type: Hijacking, armed assault
- Attack location: United States Department of Defense; Arlington, Virginia
- Targeted entity: U.S. government and military
- Perpetrator group: Al-Qaida
- Weapons used in attack: Knives, passenger aircraft, jet fuel
- Level of property damage: Catastrophic (likely more than $1 billion)
1. 9/11 Terror Attack on New York City
- Total number of fatalities: 2,770 (97.0% American citizens)
- Number of non-fatally wounded: 21,756 (97.0% American citizens)
- Date of incident: Sept. 11, 2001
- Attack type: Hijacking, armed assault
- Attack location: World Trade Center Complex; New York City, New York
- Targeted entity: Private citizens and property
- Perpetrator group: Al-Qaida
- Weapons used in attack: Knives, passenger aircraft, jet fuel
- Level of property damage: Catastrophic (likely more than $1 billion)
Top Gaining Stocks
Top Losing Stocks