Teenager Athing Mu became the first American woman to win the Olympic 800m crown in more than half-a-century Tuesday, producing a superb display of front-running to win the gold.

The 19-year-old prodigy from New Jersey, who only turned professional in June after a successful college career, led from start to finish to win in a new US national record of 1min 55.21sec.

Britain's Keely Hodgkinson -- another 19-year-old -- took silver in 1:55.88 while Raevyn Rogers of the United States took bronze in 1:56.81.

Mu, whose parents moved to the United States after fleeing civil war in Sudan, is the first American woman to win the Olympic 800m title since Madeline Manning at the 1968 Mexico City Games.

"It's awesome," said Mu. "I feel like I've just accomplished one of my goals.

"I just wanted to be a medallist."

Mu said that her ambition grew bigger than that as it got closer to the final.

"I wasn't really putting gold on that, but as it got closer to the final today, I was like, 'Yeah, we want gold'," she said.

"It's an accomplishment that I wanted off my list."

It was a remarkable display from Mu, showing a confidence and maturity that belied her relative inexperience in top-level track and field.

Drawn in lane three, Mu glided into the lead before the 200m mark and never looked back, clocking a brisk 57.82 first lap.

She then cranked up the pace in the closing 200 metres, pulling away from the field to cross the line with a comfortable margin of victory from the fast-finishing Hodgkinson.

This year's Olympic 800m took place in the absence of 2012 and 2016 gold medallist Caster Semenya of South Africa.

Semenya has been barred from competing over 800m by World Athletics' testosterone-reducing regulations.