Team USA's Simone Manuel, who won silver in the 50m freestyle at the Rio Games, missed the event's Olympic final after a sixth-place finish in the semifinals.
It's likely Manuel's last race at Tokyo 2020.
Compatriot Abbey Weitzel, who touched down in 24:19, took second in the semi and will appear in the finals.
Australian winner Emma McKeon won the race in an Olympic Record time of 24:00 flat.
SEE MORE: Rio 2016: Simone Manuel ties for gold in 100m free, new OR