Taking a 3-0 lead at the break, USA went on to score 7 more goals in the second half to hand PNG their second 10-0 hiding of the Tri-Nations friendly series.
Kelcie Hedge continued the onslaught in the 54th minute from a header that flew past PNG keeper Lavina Hola.
This triggered a flurry of goals with USA reaching double figures in extra time.
Japan finished undefeated in the Tri-Nations, beating PNG 10-0 and then USA 5-0. USA managed the one win over PNG while the home side finished winless.
