Their farewell match this year took place in front of 24,377 spectators at the Kumagaya Rugby Ground north of Tokyo, reports Efe news.
The opening minutes of the game were tense, with a disallowed try for Argentina and a steely US team attack that hit the South American side's tough defensive line.
Then, in the 18th minute, Argentine center Juan Cruz Malloa slipped through the US defence before offloading to Nicolas Sanchez, who scored and then converted the try to open proceedings 7-0.
It was a moment of glory for the fly-half, who was subbed off in Argentina's first game of the tournament, came on from the bench in the second, and did not even appear in Mario Ledesma's squad list for the third.
Six minutes later, fullback Joaquin Tuculet got a try to bring it to 14-0 with another Sanchez conversion.
He did it again in the 34th minute, his third for the national team, although the conversion missed (19-0).
It was now time for the Americans to offer up a surprise with Blaine Scully collecting a kick to score his second for the US in what has been a lackluster showing at the tournament this year.
Malloa got things underway in the second half in the 43rd minute (33-5). Then came the turn of Jerunimo de la Fuente, who ran it down the left-wing to secure the try. Sanchez converted once again (40-5).
The US team put up a small fight with a try in the 59th minute from Paul Lasike, which was easily put over the posts by AJ MacGinty (40-12).
Argentina had more to give, however, and Gonzalo Bertanou scored in the 71st minute before Benjamon Urdapilleta (who replaced Sanchez) converted to bring it to 47-12.
Then came another from the USA in overtime, Scully taking the try this time, although the conversion was missed (47-17).
It was another special occasion for the Pumas as winger Juan Manuel Leguizamun hung up his boots at the age of 36.
The team paraded him on their shoulders for a final farewell.