New Zealand's Lydia Ko and American Jennifer Kupcho were Chun's closest challengers as they finished the day on five under.

Northern Ireland's Stephanie Meadow is eight shots off the lead.

England's Georgia Hall is one shot further back, while Mel Reid is level par and Ireland's Leona Maguire is two over after two rounds.

Chun - a previous US Open and Evian Championship winner - is seeking a first major title in six years.

Although she finished the day five strokes worse than the course-record 64 she produced on Thursday, she was satisfied with her day's work.

"I think 69 is still a great score," said Chun, "Before I started today, I really didn't want to think about yesterday. It was almost a perfect game I had [on Thursday]."

Defending champion Nelly Korda, who recently returned to golf after a blood clot, carded a 74 on Friday to finish on one over.

With the cut at three over, England's Charley Hull (+4), Jodi Ewart Shadoff (+5), Bronte Law (+9) and Charlotte Thomas (+10) as well as Scotland's Gemma Dryburgh (+10) did not make it to the weekend.

Women's PGA Championship organisers doubled the tournament's prize money this year, with a record $9m (£7.3m) purse on offer.

The winner of the Maryland event, the third major of the women's season, will collect $1.35m (£1.1m).