Florida State's Becky Edwards opened the scoring in the 11th minute and California's Alex Morgan added a pair of second-half goals for the Americans, whose six points in two games assure them a place in the quarterfinal round.
The shutout was the second in a row for the Americans.
"I was very pleased with my defense today," said Coach Tony DiCicco, "and I had a feeling that if our defense was good then we would get a goal eventually."
Nov. 22 in Chillan
USA 3 Argentina 0. Goals: Edwards 11, Morgan 53, 90.
USA -- Naeher, Reed, Fowlkes, Marshall, Klingenberg, Edwards, Nairn, Wells (Winters, 56), Leroux, Morgan (DiMartino, 90+), Washington (Enyeart, 56).
Argentina -- Callelo, Chavez, Espindola, Hernandez (Bracamonte 57), Mendieta, Bedini (Larroquette, 81), Jaimes, Potassa, Mandrile, Gomez (Ferrero, 86), Santana.
Yellow Cards: USA -- Edwards 75, Klingenberg 79; Argentina -- Chavez 24, Callelo 54, Santana 87, Bracamonte 90.
Referee: Cristina Ionescu (Romania).