Catriona Matthew posted a 2-under-par 70. She stands in fifth place alongside Seol An Jeon.
Kerr opened with three straight pars at Las Vegas Country Club. She got on the scoreboard with a bogey at the par-4 fourth, where she missed the green. She got that stroke back when she rolled home a 30-foot birdie putt at the seventh.
She came right back by sinking a 15-footer for birdie at the next. Kerr found water at the ninth, which led to a bogey dropping her back to even par. She came back with a two-putt birdie at the next.
Kerr's second to the par-4 11th came up short and she was unable to save par. She moved back into red numbers for good when she dropped a wedge within 9 feet for birdie at the 13th.
The 2002 Longs Drugs Challenge winner drained a 15-footer for birdie at the 15th and capped her scoring with a 12-foot birdie on No. 17.
'I was kind of 1 over through six holes or something and I said to my caddy, let's just see if we can get something started,' Kerr said. 'I made a really long putt on seven off the fringe. That was really, really good and I rode a little momentum into eight.
'I birdied a hole, I bogeyed a hole. And then, you know, I got a couple in a row, and I could have even made another one on 18, so I was able to get some positive momentum into the last six holes.'
Prammanasudh was steady throughout her round. She dropped a 7-iron within 8 feet for birdie at the fourth. She came back with another 8-foot birdie at the sixth.
The 2003 Futures Tour money leader sank a 4-foot birdie at the 11th to get to 3 under. She parred in for her share of the lead.
'I started off a little shaky actually, I missed the first two fairways, the first three greens. But I was able to get up and down,' said Prammanasudh. 'It's hard, you know, I was very satisfied with the way I played because the wind out there is crazy because it will be against you one second, and then a crosswind the next second, and it's really just how lucky you get when you impact your ball.'
Taylor picked up birdies at the fifth and eighth to head to the back side at minus-2. She drained birdies on the 10th and 12th for climb to 4 under. However, she fell back into a share of the lead with a bogey on No. 16.
Gallagher-Smith picked up her first birdie at the fourth. She later converted back-to-back birdies from the ninth. She drained a 16-footer for birdie at the 14th to move to minus-4. A three-putt bogey on No. 17 dropped Gallagher-Smith back into a tie for the lead.
'I pretty much knew it was going to be breezy,' said Gallagher-Smith. 'It wasn't too bad early on and then I just think coming in that back nine the last few holes the wind really swirls a lot, so it's kind of hard picking clubs out there. But I managed to take care of all of that.'
Gloria Park, amateur In Bee Park and tour rookie Reilley Rankin head a group of 12 players at 1-under-par 71. Beth Bauer and Grace Park lead a large group one shot further back at even par.