Brianna Rollins has succeeded the absent Sally Pearson as Olympic 100m hurdles champion, leading an American sweep of the medals in Rio.
The winning time of 12.48 seconds was well outside the 12.35 which Pearson ran to claim gold four years ago in London.
Nia Ali pocketed the silver in Rio in 12.59 and Kristi Castlin took the bronze in 12.61.
"My 12.35OR STAYS maybe I can break it in 4 years!! Well done @usatf clean sweep @ItsPooda @Bri_Rollin @KristiHollywood well done girls," tweeted Pearson, who was ruled out of the Rio Games with a hamstring injury.
Rollins added the 2016 Olympic title to the 2013 world championships crown, when she relegated Pearson to second spot in Moscow.
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Such is the Americans' depth in the event that they did the trifecta in Rio without world record holder Kendra Harrison, who failed to earn a berth on the team.
Jamaica's Elaine Thompson became the first woman since the late Florence Griffith-Joyner in 1988 to complete the Olympic 100m-200m double when she won the half-lap event in 21.78 on Wednesday night.
Reigning world champion Dafne Schippers from the Netherlands took silver in 21.88 and the bronze went to American Tori Bowie (22.15).
"My school motto was 'let the light shine' and I let my light shine tonight," said Thompson.
"It's a big surprise to me because I have had a hamstring injury.
"You must overcome these things and tonight I am standing here with a gold."
Jamaican Usain Bolt stayed on track for a historic sprint triple triple by clocking the fastest time of 19.78 in the men's 200m semis.
Bolt has already pocketed a third Olympic 100m title in Rio and will also go for gold in the 4x100m relay later in the Games.
Bolt crossed the finish line laughing with Canadian 100m bronze medallist Andre de Grasse, who clocked 19.80 and pushed him all the way.
"He was supposed to slow down," joked Bolt.
"I said, 'What are you doing, it's a semi-final?' But I think he wanted to push me.
"I was a bit lazy, I don't know why, but I executed and got round."
Controversial American Justin Gatlin was eliminated, after clocking 20.13 to finish ninth overall.
Gatlin - who was second to Bolt in the 100m in Rio - has served two doping bans.
Earlier on Wednesday, Conselsus Kipruto from Kenya won the men's 3000m steeplechase.
