Dominating the afternoon fourballs to take a 5-3 overall lead.
In a format that habitually favours the Europeans, Davis Love's team took the fourballs 3-1 after sharing the alternate ball foursomes 2-2 in the morning's play.
All 24 players were in action during a day which started so promisingly for Europe but which ended so positively for the US who are out to regain the trophy lost in Wales two years ago.
"Just everybody played real well and hung in there and had a lot of fun. Seemed like as the sun came out, we just got better and better," Love said.
The American heroes were rookie Keegan Bradley, showing passion and talent in securing two points with Phil Mickelson, who was winning a record ninth US cap, and Bubba Watson who fired up the big Chicago crowd with his attacking game.
"This is one of the most emotional days playing in a Ryder Cup that we'll ever have," Mickelson said.
"It gets emotion out of every player, good or bad, and this has been one of the biggest highs that we've had.
"I just love playing with Keegan. He's just played so good all day and it's just kept me up the whole time. It's been awesome."
Tiger Woods was out of sorts for most of the day, losing twice with established partner Steve Stricker.
"I didn't play very good this morning at all," Woods said. "I was hitting it awful and not doing anything well. But I hit it good this afternoon."
For Europe, Belgian rookie Nicolas Colsaerts excelled with an eagle and eight birdies, but eyebrows were raised over captain Jose Maria Olazabal's non-selection of Ryder Cup firebrand Ian Poulter for the fourballs after he and Justin Rose had beaten Woods and Stricker in the morning.
World No.1 Rory McIlroy played both sessions with fellow Ulsterman Graeme McDowell and they met with mixed success, winning in the morning and losing in the afternoon.
"Obviously it was just a high to end this morning and then to try to get ourselves back for the afternoon, just didn't start as well as we would have liked," McIlroy said.
The US charge in the afternoon was spearheaded by crowd-pleaser Watson who teamed up with US Open champion Webb Simpson to crush Paul Lawrie and Peter Hanson 5 and 4.
Great Putting displays
Then, the on-fire pairing of Mickelson and Bradley led all the way to see off a tired-looking McDowell and McIlroy 2 and 1 in what was the pick of the later matchups.
Dustin Johnson and Matt Kuchar made it 3-0 with a 3 and 2 win over Rose and Martin Kaymer before Colsaerts put on one of the greatest putting displays in Ryder Cup history to carry Lee Westwood on to a one hole win over Woods and Stricker.
Europe's most experienced Ryder Cup player Westwood said that Colsaerts effort in winning a point was vital.
"It's a massive point," he said. "If we would have lost the day three and a half to a half, it would have been difficult to come back.
"We've still got our backs against the wall, but two down after the first day, it could have been worse."
Earlier in the day, the atmosphere at Medinah, at 7 658 yards the longest course in Ryder Cup history, was electric as McDowell got proceedings under way shortly after the crack of dawn in chilly conditions.
But it soon deflated as Europe took an early command, leaving US skipper Love complaining that it was all too quiet for his liking.
Europe were ahead in all four of the foursomes as the lead group stood on the eighth green, but it was Mickelson and Bradley that led the US fightback.
At one stage the advantage was briefly with the Americans, but a share of the spoils to get things going seemed a fair result for the morning's play.
It was the first time that had happened in the opening session of the Ryder Cup since 1997 at Valderrama in Spain.
All that was to change in the afternoon though as the United States took command and Europe will need to quickly redress the balance in Friday's second round of foursomes and fourballs.
Olazabal said he had been disappointed with the performances of some of his players.
"Obviously we are going to have our players' meeting tonight after the boys have rested and have dinner. We will address what happened today," he said.
"And I'm going to make it clear to the boys that they need to step it up. They need to play better golf – simple as that.
The odds are against him. In the last 15 Ryder Cups the team leading after the first day has eventually gone on to win the trophy 12 times. – Sapa-AFP