The Oklahoma City bombing was a terrorist attack on April 19 1995 aimed at the U.S. government in which the Alfred P. Murrah Federal Building was bombed in an office complex in downtown Oklahoma City, Oklahoma. The attack claimed 168 lives and left over 800 injured. Until the September 11, 2001 attacks, it was the deadliest act of terrorism on U.S. soil.

Shortly after the explosion, an Oklahoma Highway Patrol officer stopped 26-year-old Timothy McVeigh for driving without a license plate and unlawfully carrying a weapon. Within days after the bombing, Timothy McVeigh and Terry Nichols were both arrested for their roles in the bombing. Investigators determined that McVeigh and Nichols were sympathizers of an anti-government militia movement and that their motive was to avenge the government's handling of the Waco and Ruby Ridge incidents (the bombing occurred on the anniversary of the Waco incident). McVeigh was executed by lethal injection on June 11, 2001. Nichols was sentenced to life in prison. A third conspirator, Michael Fortier, who testified against McVeigh and Nichols, was sentenced to twelve years in prison for failing to warn the U.S. government. As with other large scale terrorist attacks, conspiracy theories dispute the official claims and point to additional perpetrators involved.

The attacks led to widespread rescue efforts from local, state, and federal and worldwide agencies, along with considerable donations from across the country. As a result of the destruction of the Alfred P. Murrah Federal Building, the U.S. government passed legislation designed to increase protection around federal buildings and to thwart future terrorist attacks. Under these measures, law enforcement has since foiled over fifty domestic terrorism plots. On April 19, 2000, the Oklahoma City National Memorial was dedicated on the site of the Murrah Federal Building to commemorate the victims of the bombing and annual remembrance services are held at the time of the explosion.