Amtrak’s worst wreck in terms of deaths was the Sept. 22, 1993, derailment outside Mobile, Alabama, when the Sunset Limited plunged off a bridge and caught fire in the pre-dawn hours. Forty-seven passengers and crew were killed and 103 injured in what became known as the Big Bayou Canot rail accident. The bridge over that arm of the Mobile River had been damaged by a barge shortly before the passenger train started to cross it. The worst wreck as far as overall casualties was the 1990 collision of an Amtrak train with a Boston commuter train that left 453 injured, but there were no fatalities.
There is no record of an Amtrak wreck in Missouri having 20 casualties or more, according to Wikipedia’s list of serious accidents. Prior to Monday’s wreck, in which at least 50 were reported injured along with multiple deaths, the Southwest Chief and its predecessor, the Southwest Limited, had been involved in three serious wrecks along its 2,265-mile route from Los Angeles to Chicago that met that 20-casualty threshold.