"It was a battle," Law said. "Seemed to feel like every time I would make a birdie and try and build on it I would have an unforced error couple holes later and make bogey and be back to where I started."
The Englishwoman had six birdies and three bogeys. "Mistakes happen," Law said. "I'm just going to try to minimize that for the rest of the tournament. I'm creating enough chances to where I can keep shooting some low scores."
Song, tied for the first-round lead with Law and Anna Nordqvist, also had a 68. "Overall, very happy with my round," Song said. "I managed to make great scrambles here and there and just made a couple birdies coming in. Very happy about my round."
Concolino had five birdies and a bogey in a 67 alongside Song in the first group of the day off the 10th tee. "Jennifer and I are good friends," Concolino said. "We were just talking about it in the tent. We fed off each other. She made a birdie, I made a birdie. She was making birdies on top of me."
Song had five birdies and two bogeys. "I had a rocky start. I started with a bogey on the first hole and managed to come back with a birdie on my third," Song said. "Just while I was just struggling, Jacqui was having a birdiefest so I was just like, 'Wow, I need to keep up with her.'"
The three leaders are winless on the LPGA Tour. Carlota Ciganda and Madelene Sagstrom were a stroke back in the final event before the U.S. Women's Open next week at the Country Club of Charleston in South Carolina. Ciganda had a 65, and Sagstrom shot 66.
The tour was off the previous two weeks. "I think it's been good these two weeks," Ciganda said. "I feel rested. I feel ready to go again. I was quite tired after San Francisco. I went back to Spain for two weeks and just rested, stayed with my family, friends, ate some good food."
Nelly Korda, Nasa Hataoka and Ashleigh Buhai were 7 under. Returning from a three-week break, Korda had a bogey-free 66. "Felt a lot better," Korda said. "I was a little fidgety on the front because I hadn't played for three weeks. I came off a missed cut, so got the bad round kind of out of the way yesterday and was really aggressive today. Made some solid putts and took every opportunity I could.
"I didn't play golf for a week. I just worked out, hung out, went to the beach. Kind of gave my mind a rest. I was on the road for six weeks and that takes a toll on you. Just made sure I relaxed." Hataoka and Buhai shot 67.
Brittany Lincicome had a 69 to get to 5 under in her final event of the season as she prepares for the birth of a daughter in early September. Nordqvist (72), third-ranked Sung Hyun Park (66), Brooke Henderson (71) and Jessica Korda (68) also were 5 under.
Defending champion Ariya Jutanugarn and top-ranked Jin Young Ko were 3 under after 68s. No. 2 Minjee Lee was 1 under after a 73. Lexi Thompson missed the cut by a stroke with rounds of 71 and 72.