'This is unbelievable,' said DiMarco, who won 4 1/2 points for the American side. 'To do it for the teammates here, I'm so happy. What can you say when the greatest player in the world has enough trust in you to put you in last?'
DiMarco's birdie gave the United States the 18 points needed to win the Cup.
That contest headed back to No. 1, but DiMarco drained his putt, resulting in a halve for Mickelson and Cabrera.
In the end, the United States won 18 1/2 - 15 1/2, giving captain Jack Nicklaus his first Presidents Cup win in three tries as the leader. It was the first American victory in a Presidents Cup or Ryder Cup since the 2000 Presidents Cup, and for Nicklaus, possibly his last bow in golf's stage.
'It looked like we were going to win early, then they came back,' said Nicklaus. 'It feels a lot better to have a win. I may never captain another team, I may never play another round of golf. If I end my career this way, it's a pretty good way to end it.'
The U.S. had a commanding advantage early with wins from Justin Leonard, 4 and 3 over Tim Clark, David Toms, 2 and 1 over Trevor Immelman and Kenny Perry, a 4 and 3 victor over Mark Hensby.
One early match went against the Americans and that was one of the bigger shockers. Tiger Woods, who has not lost a singles match in international team competition since the 1997 Ryder Cup, battled injuries, but ultimately fell to Retief Goosen, 2 and 1.
Fred Couples earned a spectacular point for the Americans with an 18-foot birdie putt at the last to knock off world No. 2, Vijay Singh, 1-up.
Jim Furyk, undefeated for the U.S. with a 3-0-2 mark, handled Adam Scott, 3 and 2, but the Internationals staged a comeback midway through the Sunday singles.
Mike Weir toppled Scott Verplank, reigning U.S. Open champion Michael Campbell bested Fred Funk and Peter Lonard beat Stewart Cink. All three matches went to the International side by a 3 and 2 margin.
Davis Love III assured the U.S. at least a tie when he bettered Nick O'Hern, 4 and 3, but it was the heroics of Mickelson and DiMarco that allowed the U.S. to remain undefeated on home soil.
Both of the final two matches were even late on the back nine and the Internationals took the lead in both.
Cabrera, from the left rough, hit a wedge to 8 feet at the 17th. Mickelson came up short of the putting surface from 100 yards out, but chipped inside 2 feet and was conceded par. Cabrera ran home the birdie putt to move 1-up with one to play.
After Cabrera won the 17th, Appleby, in the match behind, hit his approach to 3 feet at 16 and won the hole. DiMarco went from the right rough to the left rough by the green and would need to win 17 and 18 to get a full point.
Cabrera found the rough off the tee at 18 and Mickelson drove into the fairway. The long-hitting man from Argentina hit a great approach 15 feet past the hole, but Mickelson stopped his second 4 feet short of the cup. Cabrera ran his birdie putt past the hole, but Mickelson stepped up and drilled his putt to draw even with Cabrera.
Mickelson thought he halved the match and gave the U.S. the 17 1/2 points, which would be enough to clinch. He shook hands with Cabrera, then the rules official walking with the group and threw his arms in the air when he found out he had to go back to No. 1, with the Cup still in the balance.
'Captain Nicklaus said there were no halves, but I didn't quite grasp what he meant by that on 15,' said Mickelson. 'It was fine. It turned out just great.'
DiMarco rallied at 17 with an approach that stopped 15 feet from the hole. Appleby, who was always ahead of DiMarco in the fairway with their difference in distance, airmailed a wedge off the grandstand and chipped his third 10 feet past the stick. DiMarco left his putt on the lip, but Appleby missed his par try and it was all-square with one to go.
Appleby had the advantage off the tee at the closing hole as he found the short grass. DiMarco drove in the right rough, but hit his approach to 12 feet. Appleby, from 87 yards, hit it to 15 feet, but missed the putt.
DiMarco did not, thus ensuring there would not be another tied Presidents Cup.
In 2003, Woods and Ernie Els had a playoff that was halted for darkness with the sides tied. Nicklaus and International captain Gary Player decided to share the Cup.
'Golf benefited from today,' said Player. 'Congratulations to the U.S.A. That putt that Chris holed on the last, I really take my hat off to him. They played better.'
Two other matches proved crucial in the outcome, each side taking an unlikely point.
Couples and Singh were all-square after Singh won the 16th and both players missed short birdie putts at 17. Neither player hit the fairway at 18, but Singh ran through the green with his second, while Couples' ball stopped 18 feet past the flag. Singh's chip nearly went in, but ran past the hole, on almost the exact line of Couples' putt.
Couples, a captain's pick who has not played in an international team competition in seven years, sank the putt, raised his arms in the air, dropped the putter and listened as the galleries chanted, 'Freddie.'
'To hole that putt in front of everyone...I thoroughly enjoyed every minute of it,' said Couples, who holed a long putt to beat Singh in 1996 and secure the Cup for the U.S. 'This is certainly exciting for me.'
Woods was 1-up through eight holes, but Goosen played solidly with a 50-foot eagle putt at the third. He holed another putt of that length to win the ninth and square the match.
Goosen won the 10th with a routine two-putt par after Woods missed the fairway. Woods drew even at 11, lost the next hole, but once again knotted things with a win at 14 when Goosen missed the green at the par-3.
Woods drove the ball erratically all match long and it happened again at the 16th. His drive trickled into the trees and he had a walnut against his ball. Woods managed to get into the rough left of the green, but Goosen landed 25 feet from the hole. Woods chipped on, but Goosen rolled in yet another long putt to go 1-up with two to play.
By the 17th, Woods was in pretty obvious pain with an injury somewhere to his left side. Woods once again mis-hit a drive and was forced to hit from one knee out of the trees on the right. His third landed 15 feet from the hole, but Goosen was 25 feet from the hole in two.
Goosen came up 3 feet short, but Woods missed his putt, then conceded the South African par and the match.
'It was giving me a little problem the last nine holes,' said Woods, who received therapy on his back both Friday and Saturday. 'I had my opportunities. I didn't make the putts.'