Europe continue to face an uphill battle to lift the Solheim Cup for a record fourth time in succession after the second day's foursomes finished 2-2.
Suzann Pettersen's side threatened to halve their overnight deficit when they led in three of the four matches for much of the morning session, but in the end were grateful to remain four points behind at 8-4.
Cheered on by former US president Barack Obama, who is a member at Robert Trent Jones Golf Club, the home side had established a 6-2 overnight advantage, the largest first-day lead in the competition's history.
A 4&3 win for Lexi Thompson and Lauren Coughlin over Maja Stark and Georgia Hall on Saturday briefly extended the lead before Anna Nordqvist and Celine Boutier defeated Lilia Vu and Sarah Schmelzel by the same margin.
World number one Nelly Korda and Allisen Corpuz then claimed their fourth foursomes win in succession by closing out Emily Pedersen and Carlota Ciganda on the 18th, the European pair having led by two holes at the turn.
The American duo enjoyed an outrageous slice of luck on the par-five 14th when Corpuz thinned her second shot but saw the ball slice around the water guarding the green and run up the putting surface to leave Korda just 15 feet from the hole.
Korda duly converted the eagle putt to move ahead in the match for the first time and although a par was good enough for Pedersen and Ciganda to win the 15th, they three-putted the 17th to fall behind again.
Charley Hull and Esther Henseleit were also in danger of squandering a two-hole lead with four to play when they lost the 15th to a long-range birdie before Hull badly misjudged her approach to the 17th, flying it more than 20 yards over the green.
However, with the match now all square, Hull immediately made amends with a huge drive on the 18th to set up Henseleit to hit a stunning approach to tap-in range and seal a vital win.
"I feel like I hit my irons pretty good today, but after I hit the shot on 16 pretty close I was pretty pumped," Hull said.
"And then on 17 I just airmailed the green. I was just super pumped. It should have been one less club.
"Then on the last I just bulleted my driver so far and I was so glad I didn't have that shot in. Esther just completely stiffed it to half a foot, so I was thankful for that."
