That prize finally went to Allyson Felix, who twice missed out and had to settle for silvers at the Beijing and Athens Olympics. Felix won in 21.88 seconds, beating Jamaica's Shelly-Ann Fraser-Pryce, who won the 100 four nights earlier, by .21 seconds. American Carmelita Jeter added bronze to the silver she won in the 100 metres.
"I mean, finally. It's been a long time coming," Felix said, reflecting on her two previous Olympic losses to Jamaican Veronica Campbell-Brown. "To twice lose to the same person, it's been tough. But it's all paying off."
Campbell-Brown finished fourth, unable to become the first woman in track and field to win gold medals in the same individual event at three consecutive Olympics.
Aries Merritt added to the perfect sprint night for the United States, coming first in the 110-metre hurdles final ahead of compatriot Jason Richardson. Brittney Reese won the long jump title soon afterward to complete the triple for the Americans.
Adding to the night's U.S. successes, Misty May-Treanor and Kerri Walsh Jennings took their third consecutive Olympic beach volleyball gold medal, beating fellow Americans April Ross and Jennifer Kessy. It was the Olympic farewell for May-Treanor, who has said she would like to move on.
The night's successes brought the United States to a total of 34 golds — two behind China, which topped the rankings with 36 by end of Wednesday. Both have 22 silver medals each, while the U.S. has 25 bronzes to China's 19.
In the men's 200, Jamaica's Usain Bolt won his semifinal heat in 20.18 seconds, moving closer to becoming the first man with two Olympic golds in the 200 metres. The final is Thursday night.
Events on the track began taking centre-stage early in the day. Two women who created international headlines made appearances in the 800 metres. It was Caster Semenya's first, and Sarat Attar's one and only.
Attar, wearing a white headscarf, green long-sleeved shirt and black leggings, became the first Saudi woman to compete in Olympic athletics. With the 80,000-capacity crowd cheering, she finished her heat in 2 minutes, 44.95 seconds — more than 40 seconds behind the fastest qualifier — and failed to advance to the semifinals.
"It is the hugest honour to be here to represent the women of Saudi Arabia," Attar said. "It is an historic moment. I hope it will make a difference."
Semenya, making her Olympic debut three years after being forced to undergo gender tests, finished second in her 800 heat. The South African runner was sidelined for nearly a year while track and field's governing body, the IAAF, decided whether to allow her to compete after she won the 2009 world title at age 18. She was tested and eventually cleared to return to action in 2010, then was the runner-up at last year's world championships.
Semenya carried South Africa's flag at the opening ceremony in London and is a leading medal podium chance in the 800.
"It was a tactical race, I wanted the race to be a fast one," Semenya said. "I have to run a sub-two (minutes) race to be a contender."
In finals away from the track, Japan won two wrestling golds — in the 63-kilogram and in the 48-kilogram women's freestyle divisions.
Earlier, a 36-year-old canoeist gave Norway its first gold medal of the games as China and the United States continued their intense games-long competition for top spot on the medal table.
Eirik Veras Larsen won the K-1 event over 1,000 metres at Dorney Lake west of London. Hungary won two of the four canoe and kayak gold medals — Rudolf Dombi and Roland Kokeny had a photo-finish in the men's 1,000-metre K-2 and the Hungarian women's quartet ended the 16-year dominance of their German rivals in the K-4 500.
Steve Guerdat of Switzerland, riding Nino des Buissonnets, won the gold medal in individual show jumping after jumping cleanly in Wednesday's final two rounds of competition.
In the English Channel off Weymouth, Nathan Outteridge and Iain Jensen sailed three laps of honour to collect their gold medals in the 49er skiff class, giving the Australian sailing team its second gold in the regatta and fifth overall.
China won the men's team event in table tennis, completing a sweep of all the gold medals in that sport and picked up a gold later in taekwondo, when favourite Jingyu Wu won the women's 49-kilogram class.
The last medal of the night went to Spain in the men's taekwondo's 58-kilogram division.