For the longest time, 17-year-old amateur Hye-Jin Choi was in control on this final day, well on her way to becoming just the second amateur to win this tournament, joining Catherine LaCoste (1967).
With the victory, Park won her first major title and the 900-thousand USA dollars top prize.
After weeks of uncertainty, the U.S. Women's Open stopped being about President Donald Trump, his course and his views toward women and it turned out to be what the USGA wanted: a good tournament on a good course.
But that dream died on the shortest hole of the course when she pushed her tee shot on the 147-yard 16th into the water and wound up with a double bogey.
Feng's only major victory came at the 2012 LPGA Championship, her first USA triumph.
In her US Women's Open debut previous year, Park led by two shots after 36 holes but closed with back-to-back 74s and settled for a share of third.
"Obviously I am hitting it good and I am putting it good", Lee said.More news: Taiwan's reckless comments on dissident Liu very unsafe : China
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Sung Hyun Park gained a reputation in her native South Korea as being an aggressive player, so aggressive that fans there gave her a nickname that loosely translates in English to "Shut your mouth and attack". Feng had a birdie on the final hole Saturday afternoon, but she has a total of 10 overall through three rounds.
"It will be nice if I could get the money but I think my primary goal was to come here and compete so, to me, getting this second place as runner-up actually means more to me and it's a greater honour", she said. But she blasted out into the fairway, dropped her approach three feet from the cup then sank the putt to conclude a one-under 71 third round.
"I think one of the most hard things is to to stay focused and keep that concentration level up", she said, "because I know that once you lose it, your playing is going to go just sideways". But in the final round she birdied the second, fifth, eighth, 12th, 15th and 17th holes to be two shots in front of Feng by the 18th.
"That nickname, I guess kind of came from my fans past year", said Park. She has followed with six more US LPGA titles, most recently winning in May at Ann Arbor, Michigan.
A day after her worst, Minjee Lee bounced back brilliantly to record her best US Open score today in a belated charge to a share of 11th. The weather really hasn't bothered me.
Mi Jung Hur and So Yeon Ryu tied for 3rd two shots behind the runner-up and four from Park. "Last year, I just made the cut so actually this year is such an improvement".