LONDON -- The race was still somewhat close when Allyson Felix grabbed the baton.
Then it wasn't.
She shifted into that Allyson Felix gear and opened up a lead that grew wider and wider during the second leg of the 4x400-meter relay Sunday at the world championships.
The final two legs of the race were a formality, with the Americans winning in a cakewalk. It was Felix's 11th world gold medal, tying her with Usain Bolt for most in the history of the championships. What's more, it was her 16th career world medal -- a mark that belongs solely to her.
It was a banner night for Felix and a banner 10 days at the worlds for the Americans, who brought home a team-record 30 medals, including 10 of the gold variety.
The U.S. squad finished the 4x400 in 3 minutes, 19.02 seconds. Previously, the largest margin of victory at worlds in this race was 3.32 seconds. The U.S. won this one over Britain by 5.98, and Felix's second lap helped set the tone.
"It's really special. I feel like the sport has really given me so much, and I hope I have given a little bit back in return," the 31-year-old Felix said. "It's a special thing to be able to look back and see what I have done over the years."
As she finished her celebration lap, the crowd was applauding for Bolt. He was taking one last ceremonial lap to say farewell to the fans.
Felix still wants to race -- at least to the 2020 Tokyo Olympics. When she's finished, though, there will be no fancy displays. That's not really her thing. But she's glad Bolt got that sort of recognition.
"It was really neat to see that for him, see the appreciation people have for what he's done," said Felix, who has nine Olympic medals, including six golds, to go with her record haul from worlds. "Sometimes, you take it for granted. There's so much work that comes into this, and to be consistent over the years, sometimes that gets lost. It's cool to see people appreciate it."
This has been a roller-coaster championship for Felix. She didn't have her traditional kick in the final of the 400 and settled for bronze in a race won by teammate Phyllis Francis, who anchored the 4x400 relay. Felix also helped the 4x100 relay team to a gold medal.
Those two relay golds are nice and all, but they don't make up for the one that slipped away in the 400.
"Unfortunately, that's not how it works. That's not how I am," Felix said.
About all those world medals: She doesn't have any of them. But she can visit them anytime she likes -- at her parents' house. They hold onto them for safekeeping.
"I really don't know what they do with them," she joked. "I guess they look at them sometimes. They're really proud."
She's proud of this: helping to inspire the next generation of American sprinters.
"I think I've been able to see the impact I've had on young kids and getting to talk to people," Felix said. "It's neat to see the impact you've had on someone's life."
Like teammate Quanera Hayes, who handed the baton to Felix in the 4x400 race. Or Shakima Wimbley, the third leg of the relay.
"She's a good person to look up to," Hayes said. "She's such a sweet soul, a sweet spirit."
Growing up, Hayes' younger sister was more of a track fan, and one of her favorites happened to be Felix. When Hayes was in London, her sister called to ask if she had met Felix. Hayes said she was having dinner with her.
Later, they called Hayes' sister, who was recovering from a motorcycle accident.
"To see Allyson talk to her, my sister was just ... on cloud nine. That was because of Allyson," Hayes said. "We all look up to her, respect her. And to run with her, it's just a privilege."
Besides Felix, 400 champion Phyllis Francis also won a second gold medal.
Mutaz Essa Barshim won the world high jump title by clearing 2.35 meters without a miss. The Qatari will get a chance to defend his title at home in 2019, when the world championships are in Doha.
Two-time Olympic champion Sandra Perkovic won the discus with a throw of 70.31 meters, well ahead of silver medalist Dani Stevens of Australia. She set a continental record with a throw of 69.64 meters.
Caster Semenya won her third world title in the 800 meters, using her finishing kick to sweep past the competition in the finishing straight and win with ease over Francine Niyonsaba of Burundi. She gave South Africa its third gold of the championships.
In the 5,000, Obiri ran away from favorite Almaz Ayana with 250 meters to go to deny the Ethiopian a long-distance double. She won in 14:34.86.
Kenya was the only other team besides the U.S. to break into double figures, with 11 medals overall. The African nation got two more gold on the final day, with Hellen Obiri winning the 5,000 and Elijah Manangoi leading a 1-2 Kenyan finish in the men's 1,500.
The world championships also got their only world record on Sunday, and it was in the only new event: the women's 50-kilometer walk.
Ines Henriques of Portugal bettered her own mark by finishing in 4 hours, 5 minutes, 56 seconds on the 2-kilometer loop in central London. Only seven women started the race, and only four finished.
The Associated Press contributed to this report.