Biles continued her dominance Sunday in Rio de Janeiro.
The 19-year-old gymnast won her third medal by astonishing in her signature event: the vault.
She averaged 15.966 to edge Russia's Maria Paseka and Sweden's Giulia Steingruber for the top prize.
The gold medal was Biles' third of the Summer Games. She is the first-ever American woman to win in the Olympics on vault and win three gold medals in one Olympics in gymnastics.
"Final win for Phelps. World record for Ledecky. 3 #1 finishes for Biles," President Barack Obama tweeted. "That's how #TeamUSA gets America to 1000 golds-way to make history."
Biles' single vault score of 16.033 was the highest score ever in a vault final in an Olympics or world championship.
"I looked up to Alicia Sacramone and McKayla Maroney much on vault, so that is very exciting," Biles told Yahoo Sports.
Final win for Phelps. World record for Ledecky. 3 #1 finishes for Biles. That's how #TeamUSA gets America to 1000 golds-way to make history.— President Obama (@POTUS) August 14, 2016
RUNDOWN IN RIO
Matt Kuchar began the day for the United States by cashing in for a bronze medal. Kuchar shot a medal-round 63 to finish in third place in the golf tournament. The prize was Team USA's first Olympic golf medal since 1904.
The United States women's basketball team clinched Group B by bouncing China 81-51. When Bethanie Mattek-Sands and Jack Sock defeated Venus Williams and Rajeev Ram in the mixed doubles gold medal match, it meant two medals for the Americans. The former duo earned gold while the latter won silver.
The United States beat Italy 10-7 in men's water polo in match 30 of Group B preliminary play. Alexander Naddour won a bronze medal in men's pommel horse during the artistic gymnastics final. Great Britain's Max Whitlock and Louis Smith won gold and silver medals.
Madison Kocian won a silver medal for the United States in the women's uneven bars final. Russia's Aliya Mustafina won a gold medal and Germany's Sophie Scheder won a bronze medal in the event. Sarah Elizabeth Robles won a bronze medal after falling the China's Suping Meng and North Korea's Kuk Hyang Kim in women's +75 kg weightlifting.
Lashawn Merritt finished third for a bronzer medal in the men's 400-meter track final. South Africa's Wayde Van Niekerk and Grenada's Kirani James. Van Niekerk's 43.03 is a new world record.
Justin Gatlin finished second to Jamaica's Usain Bolt in the men's 100-meter track final. Bolt won the gold medal with 9.81 run in the 100. Canada's Andre De Grasse won the bronze medal in the event.
Kerri Walsh Jennings and April Ross defeated Australia's Taliqua Clancy and Louise Bawden to win a women's beach volleyball quarterfinal matchup. Benjamin Errol Provisor faces Uzbekistan's Rustam Assakalov Monday in a men's wrestling MGR 85 kg 1/8 final.
Robert Timothy David Smith later battles Azerbaijan's Sabah Shariati in a men's wrestling MGR 130 kg 1/8 final.
The United States men's volleyball team faces Mexico at 11:35 a.m. in pool A preliminary play. In gymnastics, the women's beam final is set for 2:46 p.m.