PORTLAND, Ore. - Brooke Henderson won the Cambia Portland Classic by eight strokes Sunday to become the third-youngest champion in LPGA history at 17 years, 11 months, 6 days.
The Canadian closed with a 3-under 69 at Columbia Edgewater to finish at 21-under 267, the lowest total since the event went from 54 holes to 72 in 2013.
Lydia Ko set the age record as an amateur in the 2012 Canadian Women's Open at 15 years, 4 months, 2 days. She also won the Canadian event in 2013 at 16, and won four times at 17. Lexi Thompson won the 2011 Navistar LPGA Classic at 16 years, 7 months, 8 days.
Henderson's eight-stroke margin is the largest in the history of the event and the biggest in the LPGA since Jiyah Shin won the 2012 Women's British Open by nine shots.
Henderson also became the first Canadian winner since Lorie Kane in the 2001 Takefuji Classic and joined Laurel Kean as the only other Monday qualifiers to win. Kean accomplished the feat in the 2000 Rail Classic.
Henderson earned $195,000 and has made $661,818 in 10 events this year. Last year, LPGA commissioner Mike Whan denied Henderson's age petition, preventing her from playing Q-school. Because she's assured of finishing among the top 40 in earnings this year, Henderson will earn a tour card for 2016.
Henderson bogeyed the final hole, only her third dropped stroke of the week, and had 24 birdies. She got into the field Monday with a 68, then shot 66-67-65 to take a five-stroke lead into the final round.
Pornanong Phatlum (68), Ha Na Jang (70) and Candie Kung (70) tied for second.
Henderson never allowed an opening Sunday. She made two-putt birdies at the par-5 fifth and seventh to reach 20 under, and holed a 20-foot birdie putt at the par-4 ninth to take an eight-stroke lead.
She made a 3-footer for birdie at the par-5 12th, then stumbled with a bogey at 13. Henderson made her final birdie at the par-4 17th, knocking in a 10-foot putt from the fringe.
Henderson hit her drive in a fairway bunker at 18, but with a large lead, pitched out of the sand, hit her approach to 20 feet and two-putted for bogey.
She also won the Symetra Tour's Four Winds Invitational in June in Indiana, and tied for fifth in the Women's PGA Championship - the second of the LPGA's five majors.
Defending champion Austin Ernst shot a 68 to tie for fifth at 12 under.
Morgan Pressel, second after three rounds, had a 75 to tie for 10th at 10 under.