The United States, who trailed by two after Saturday's four fourball and eight singles matches, won two of Sunday's fourball matches and eight of the 10 singles matches to beat the GB&I side by 15.5 points to 10.5 - earning them the most decisive winning margin for a visiting U.S. team since a 16 ½ - 7 ½ victory in 1987 at Sunningdale.
Following a foursomes win in the morning, with partner Conor Purcell, Fitzpatrick took out world number one amateur Cole Hammer (great name!) in the top afternoon singles game to help The GB&I team to a 7-5 lead after day one.
The Americans won two of three matches and tied the other in foursomes.
And although the English pair of Harry Hall and Conor Gough beat Stewart Hagestad and Akshay Bhatia by the same score, defeats for Scotland's Euan Walker and Sandy Scott and England's Tom Sloman and Thomas Plumb left the match score at 2-2 ahead of eight afternoon singles matches.
The U.S. team increased the series lead to 37-9-1.
The 20-year-old recovered with birdies at the fourth and sixth holes to return the match to all-square and was two-up with three holes to play after winning the 14 and 15.
The Americans actually earned more points in foursomes this weekend, 4.5-3.5, and if they end up winning it all they will be the 11th team in the past 12 Walker Cups to win more foursomes points and capture the Cup. Smalley missed that putt, but the Americans still took the hole and their first lead.
Similarly, Alex Smalley and Brandon Wu dictated play for the U.S. in their match against Somerset pairing Thomas Plumb and Tom Sloman, picking up wins on the seventh and 10 holes to go two-up.
Augenstein, Pak and Wu won for the United States.
Scott and Walker rescued a half point for GB&I after chasing Augenstein and Ogletree for much of their foursomes match.
"We feel a little dejected that we didn't get that last match", USA captain Nathaniel Crosby said.
The away side pulled another point back after Pak edged out Amateur champion James Sugrue, who did not feature in the morning foursomes - and only arrived on the tee two minutes before his match was due to start - by one hole. Norman Xiong (3-0-1) also didn't lose a match.