Canada's Brooke Henderson won the Portland Classic with a tournament-record score on her way to becoming the third player in LPGA history to win a tour event before turning 18.
The 17-year-old finished 21 under overall to surpass Suzann Pettersen's 20 under par set in 2013.
She recorded a three-under fourth round of 69 to finish eight shots clear.
Lydia Ko and Lexi Thompson are the only other players to win an LPGA Tour title before their 18th birthday.
Pornanung Phatlum of Thailand, Ha Na Jang of South Korea and US-based Taiwanese Candie Kung finished tied for second on 13 under.
The victory gives Henderson an LPGA Tour card for next season, eight months after she turned professional.
The Ontario-born player finished tied fifth at the Women's US Open and Women's PGA Championship this year.
She also claimed a tournament record score at the halfway stage of the LPGA Tour's Swinging Skirts tournament in San Francisco by shooting a nine-under 135.