The United States overturned a three-point deficit to beat Great Britain and Ireland 14½-11½ and win the Walker Cup.
Great Britain and Ireland had built up a 7½-4½ advantage at St Andrews on Saturday.
The Americans won three of Sunday's foursomes, then triumphed in six of the 10 singles ties.
The hosts won only two of the singles matches with Mark Power adding to his earlier foursomes win, while Liam Nolan and Jack Bingham also triumphed.
The US won four of the last five singles ties with Preston Summerhays, Gordon Sargent, Stewart Hagestad and Caleb Surratt all successful.
Great Britain and Ireland captain Stuart Wilson said: "We're obviously disappointed. We had a nice lead this morning that we kind of let slide quite a bit in the foursomes, but I think where the guys will be hurting the most is they'll know they haven't turned up this afternoon and acquitted themselves in the way we know they can.
"We always thought it was going to be a tight match and everything went our way yesterday [Saturday]. Six matches went up the last and we got four and a half points out of them but all the momentum seemed to be with the US side today.
"To be fair to the players, they are a great side and they handled the conditions a lot better than our guys."
US captain Mike McCoy added: "It's pretty special, it's certainly the pinnacle of my golfing life. After the morning session I felt a lot better, like we were really back in the tournament and had a chance to win this thing.
"Last night I was pretty concerned as the mornings are historically not our strong suit, but the guys played great and I think the morning was what made the day.
Watch Walker Cup highlights on BBC Two and BBC iPlayer from 23:50 BST on Sunday, 3 September.
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