Ko bogeyed holes six, nine and 10 and hit one birdie on hole 15.
Instead, she is set to contend for minor places tomorrow, ensuring her winless streak on the LPGA Tour extends beyond a year. She pumped drive after drive down the middle, driving it well past her playing partner Shanshan Feng, who was the third-round leader.
"Yes, quite a few Korean players on the top leaderboard", said Park, who said the course is similar to some in South Korea.
"I feel pretty good", Kerr said. Her tee shot landed in the water to the right of the hole. She had five 5s, a bogey and a double bogey, which came on No. 3 after a bad shot out of a bunker.
"Thank you to all of the supporters, who far out-numbered the protesters, yesterday at the Women's U.S. Open". She ended up with a triple-bogey. When asked about that after the round, she could only smile.
Her approach shot on the par-four hole found the rough above the hole on the sloping green and her chip sped past the hole and ran down the steep slope back into the fairway. The professionals were also presumably demoralized at being upstaged - golfer Lexi Thompson told the AP she was aware most of the spectators were not even really watching her play.
Meanwhile, Park takes home, $900,000 the richest prize in women's golf, and she does it because of how she played when it mattered most - the final four holes.
Feng, meanwhile, birdied the last after a run of 17 successive pars to stand nine under par. And when she made a short birdie putt at No. 17, Park had given herself a three-shot lead heading to the final hole.
The 27-year-old flew her approach shot over the green to lose the eagle opportunity.
First Lady Melania Trump and her dad joined them late in the afternoon, followed by daughter Ivanka Trump and her husband Jared Kushner - just back from the annual summit of media, tech and finance moguls in Sun Valley, Idaho - and their kids. "Anything that I can do to bring about a change in that situation, I will be there doing it".
And so Park bumped her chip into the fringe and it trundled down to the hole, almost going in. One she'll never forget.