At just 19 years old, Athing Mu is an Olympic champion.

The native of Trenton, N.J., won the 800 meters in Tokyo on Tuesday in 1:55.21 — a U.S. record, breaking a mark set by Ajee Wilson. Mu also became the first American woman to win gold in the 800 in more than a half-century.

Madeline Manning-Mims won the 800 at the 1968 Mexico City Olympics 53 years ago. Since then, the U.S has only claimed two medals — Kim Gallagher won a silver in 1984 and a bronze in 1988 — until now.

“It’s awesome,” Mu told reporters in Tokyo. “I feel like I’ve just accomplished one of my goals.

“I just wanted to be a medalist.”

Well, maybe not just a medalist. Before the Games she said she was “looking forward to standing on the podium, the middle one, and receiving the gold medal that in the future will have my name engraved on it.”

And that feeling grew stronger as the race drew closer.

“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.”

Mu led from start to finish, holding off Britain’s Keely Hodgkinson — another 19-year-old — who took silver in 1:55.88 while Raevyn Rogers of the United States took bronze in 1:56.81.

“At the end of the day, I don’t want to leave anything up to chance,” Mu told the Washington Post of her race strategy. “I don’t want to get into a race and get mixed in there and mess up my chances of reaching any of my goals. If I want to win a gold medal, I’m not going to leave it up to anyone else to decide my race.”

Mu, whose parents moved to the United States after fleeing civil war in Sudan, is coming off a brilliant freshman season at Texas A&M, where she set collegiate records in the 400, 800 and the 4×400. In June she announced she was going pro and signed with Nike.

The runner then qualified for the Tokyo Games by placing first at the U.S. Olympic trials with a time of 1:56.07, which was the second-fastest result in American history.

Though she is not racing the 400 in the Olympics, she is likely to be selected for the U.S. 4×400 team.

Before leaving for Tokyo, the city of Trenton held a celebratory sendoff in her honor at city hall. There, a huge banner with a picture of Mu and “Go for Gold” on it was unveiled. Mu is the city’s 17th resident to go to the Olympics. Before Tuesday, just two had won medals. Terrance Cauthen won a bronze in 1996 for boxing and Lawrence Low won a gold medal in 1956 as a member of the yachting team.