Days That Shaped America

Space Shuttle Challenger disintegrates 73 seconds after takeoff, killing all seven crew members, including payload specialist Christa McAuliffe, who would have been the first teacher in space; President Reagan addresses the nation on the disaster.

The siege of the Davidians' ranch in Waco, Texas in 1993 became the deadliest event in ATF's history; hear stories from the people who monitored the 51-day siege until the ranch collapsed, with many Davidians left in the building.

Survivors, paramedics and police officers tell their story of the fateful day when the Tsarnaev brothers planted bombs at the 2013 Boston Marathon.

The Oklahoma City bombing on April 19, 1995, in which 168 people were killed, was the worst attack on U.S. soil until 9/11; the bomber was Timothy McVeigh, a Gulf War veteran.

On the anniversary of the 9/11 World Trade Center attacks, those who were caught in the middle of the disaster share their first-hand experiences of the day.