Anybody 30 years old or older might remember the evening of September 11, 2001, when members of Congress from both parties met on the Capitol steps and sang "God Bless America." Together.
20 years later, members of the two parties can't even agree on what happened when people attacked the building on January 6, 2021.
Spencer Ackerman blames the change on the American response to 9/11, which he perceives as turning from a spirit of "we're all in this together" into something darker, less tolerant, and more nativist.
Ackerman makes the case in his book Reign of Terror: How the 9/11 Era Destabilized America and Produced Trump.
Listen to the author's thoughts on where mistakes were made by national leaders along the way.