With a time of 2:27.46, Seidel came in about a second ahead of Ethiopia's Roza Dereje.
Back in February that year, Seidel emerged as a surprising qualifier with a second-place finish in the U.S. marathon trials race in Atlanta. It was surprising because it was the very first time she'd ever ran a marathon.
Seidel, from Wisconsin, had been a college star at Notre Dame running long-distance races like the 3000m and 5000m, and won cross country medals in 4km and 6km events.
But a marathon? Is more than 42 kilometers.
She took to it, though - after her surprising success in Atlanta, she ran the 2020 London Marathon and finished sixth.
In between London and the Tokyo Olympics, Seidel was back in Atlanta - for the Atlanta Track Club's half marathon race at Atlanta Motor Speedway back in February of this year.
Perhaps foreshadowing her Olympic achievement, Seidel won the half marathon in Atlanta.
She said it was a "good day" after winning that race, and took note of the humidity - helpful preparation for humid Tokyo.