With 10 minutes to go until the halftime break, the Black Sticks started to earn more of the possession, finding the equaliser in the 23rd minute as a cross from Olivia Merry found Kirsten Pearce unmarked in front of goal.
New Zealand continued to attack strongly and soon forced three penalty corners in quick succession. The first two were cleared by the US but the third, in the 28th minute, resulted in a clean shot for Brooke Neal to find the net.
The second half saw the US attack for extended periods but no equaliser was forthcoming. The closest they came was in the 40th minute when a sizzling shot hit the post and rebounded away.
The victory saw the Black Sticks top the pool with 11 points, as Japan edged Australia on a countback.
New Zealand 2 (Kirsten Pearce, Brooke Neal)
United States 1 (Caitlin van Sickle)
Halftime: 2-1