The 2008 US Women’s Open champion hit eight birdies and just one bogey as she carded a r0und of 64 for a 9-under 133 total at the halfway stage of the tournament.
"I played great today," Park said. "I hit the ball very well and especially hit my short irons really good, so I gave myself a lot of opportunities and obviously putted very good today."
Rain on Thursday forced the suspension of the first round until Friday morning, delaying the start of the second round, meaning seven players were unable to complete their second round before darkness set in. They will return on Saturday morning.
Shanshan Feng, who became China’s first Major winner at the LPGA Championship earlier in June, was tied for second alongside American Brittany Lang and South Korea’s Hee Kyung-Seo.
“I’ve been working really hard at being focused on every shot,” said Lang, who recorded a round of 65.
“I lose my focus pretty easy, so that’s been my goal and I’m doing it pretty well. It’s going to be my goal on the weekend to just try to be in every shot.”
Overnight leader and rookie Sandra Changkija, was a further shot back alongside reigning US Women’s Open champion Ryu So-Yeon, Lexi Thompson, Karin Sjodin, Katie Futcher, Chella Choi and Sun Young-Yoo.
Stacey Lewis, already a two-times winner on the LPGA this season, was three shots off the pace after a second-round 64.
“I just putted a lot better,” the American said. “I think yesterday I didn’t have very good feel around the greens and I finally got some putts to go in today.
“It was actually a really easy day, so it was nice.”