Hunter Armstrong set a 50m backstroke world record of 23.71sec to qualify for the 2022 swimming World Championships at the US trials in Greensboro, North Carolina, on Thursday.
Armstrong, 21, broke the previous world record of 23.80 set by Russian Kliment Kolesnikov at the European championships in Budapest on May 18, 2021.
"I'm at a loss for words, honestly," Armstrong said after grabbing the only World Championships berth on offer in the non-Olympic event.
"It's something I've always wanted and I'm over the moon right now."
Seven-time Olympic gold medallist Caeleb Dressel booked a third individual World Championships berth with a victory in the 100m butterfly.
Dressel, who set the world record of 49.45sec in winning Olympic gold in Tokyo last year, clocked a world-leading 50.01 in Thursday's heats and won the final in 50.20.
Michael Andrew was second in 50.88 to punch his ticket to the World Championships in Budapest June 18-July 3.
Dressel, who won five gold medals at the pandemic-delayed Tokyo Games last year, had already qualified for Budapest in the 100m free and 50m fly.
Andrew returned to win the 50m breaststroke in an American record of 26.52 edging Nic Fink for the only World Championships spot by three-hundredths of a second.
Torri Huske won the women's 100m fly in 56.28 with Claire Curzan second in 56.35 -- the two fastest times in the world this season.
Carson Foster won the men's 400m individual medley in 4:09.33 with Tokyo Olympics gold medallist Chase Kalisz second in 4:10.50. Kalisz held off a furious late charge from Bobby Finke, who missed out on a World Championships berth by seven-hundredths of a second.
In the women's 400m medley, 16-year-old Katie Grimes posted a personal best of 4:36.17 to book a Budapest berth along with Tokyo Olympics silver medallist Emma Weyant, who was second in 4:37.72.
Katharine Smith set an American record of 27.12sec in winning the women's 50m backstroke, and Lilly King won the women's 50m breaststroke in 29.76sec to give herself a chance at a third straight world title in the event.