Story highlights "This is the moment I've dreamed of since I was a little girl," Shalane Flanagan says

Flanagan's first foray into the event came in 2010, when she placed second in the race

(CNN) It's been a long time running -- four decades to be exact -- since an American woman broke the finish line tape at the New York City Marathon, but Olympic medalist Shalane Flanagan did just that on Sunday.

With an unofficial time of 2 hours, 26 minutes and 53 seconds, the 36-year-old Flanagan beat three-time defending champion Mary Keitany of Kenya by a minute and one second. Times won't be official until later this month.

Flanagan crossed the finish line in tears before proudly holding the Stars and Stripes aloft. She smiled for the crowd as she wrapped herself in the American flag.

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She called the moment "indescribable," according to CNN affiliate WABC , and wept again on the podium as her name was announced.