Park, 16, followed her first-day score of 66 with a one-under 70. Chun, 17, logged a 2-under-69. The 136 is the second-lowest medalist score in WAPL history, just one stroke off the mark of 135 set by Brittany Lang in 2004. Lang was co-runner-up at the 2005 U.S. Women's Open as an amateur.
'That's huge,' said Park, of the medalist honors. 'I do have a lot of confidence in my game now and I look forward to doing well in match play. I struggled with my drives. I missed six fairways but I got up and down when I needed to and I got birdies when I needed to.'
Park was a semifinalist at the 2004 WAPL, losing to 2003 champion Michelle Wie, 2-and-1.
'It feels great,' Chun said of her medal-winning. 'It was a surprise because before I even played I was told (mistakenly) that Angela Park had shot 67. So, I thought she was nine-under. I said, 'OK, I'll just do as best as I can.' I thought I'd be third or fourth but I didn't think I'd be co-medalist.'
Marina Choi of Los Angeles is three strokes behind Park and Chun at 139 with Jackie Beers, Eun Jung Lee of Korea next at 141 at the 6,047-yard, par 71 Swope Memorial Golf Course.
Defending champion Ya-Ni Tseng shot another 76 for a 36-hole score of 152, good enough to advance her into the 64-player match play field. The cut, with no playoff needed, came at 11-over-par 153.
The best round of the day was a three-under 68 from Amanda Mathis.
Six rounds of match play begin Wednesday and conclude with the 36-hole championship final on Saturday.
The U.S. Women's Amateur Public Links is one of 10 national championships for amateurs conducted annually by the USGA. The association also conducts the U.S. Open, U.S. Womens Open and the U.S. Senior Open.