A look back at terrorism in America

Published On: Apr 15 2013 04:57:44 PM CDT   Updated On: Apr 15 2014 01:00:00 AM CDT

As America marks the one-year anniversary of the Boston Marathon bombings, look back at the history of terrorist attacks on home soil.

terrorist attacks - Shanksville
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Richard Snodgrass/National Park Service

A fourth plane, United Airlines Flight 93, was targeted at the U.S. Capitol, but crashed into a field near Shanksville, Pa., after its passengers tried to overcome the hijackers. The four hijackers died in the crash along with 40 people on the plane. Here, tokens honoring Flight 93 can be seen near the fence surrounding a construction site for a permanent memorial in May 2011.

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