At this point, it's still unclear what motivated Thomas Matthew Crooks to climb a nearby roof with an AR-15-style rifle and attempt to shoot former U.S. president Donald Trump. But he is far from the first person to make an attempt on the life of an American president. From the high-profile assassinations of Abraham Lincoln and John F. Kennedy to attempted assassinations of Ronald Reagan and Theodore Roosevelt, acts of politically motivated murder — whether successful or otherwise — are often major turning points in the nation's history.

Centre College associate professor Jonathon L. Earle walks us through the legacy of political violence in the United States, and what that history could teach us about what could happen next.

For transcripts of this series, please visit: https://www.cbc.ca/radio/frontburner/transcripts