Opener Steven Taylor set the tone with the bat with a steady 81 at the top of the order as the USA posted a decent total of 235/7 in the ICC Cricket World Cup Qualifier Play-off clash then bundled out PNG for just 118.
The victory sees the USA move to the top of the Qualifier Play-off standings with six points from four matches and Monank Patel's side will likely earn a place in the Qualifier to be held in Zimbabwe in June and July with a victory in their final match of the current event against Jersey on Tuesday.
The loss puts an end to any slim hopes PNG had of keeping their World Cup dream alive, with the Oceania side now winless through four appearances in Namibia.
The other match on Sunday saw UAE move alongside USA at the top of the standings with a narrow 28-run triumph over Namibia at the United Cricket Club Ground.
The UAE got vital contributions with the bat from Asif Khan (96 from 86 deliveries) and Vriitya Aravind (93*) when posting 267/5, and Namibia were all out in the penultimate over in reply.
The tournament hosts' chances of moving through to the next Qualifier tournament are now hanging by a thread.
Namibia take on Canada on Tuesday in what will be their final match of the tournament and need a comprehensive victory in that clash and for other results to go their way just to have any chance of finishing in the critical top two places in the standings.
UAE are in a similar position to the USA, with a match against Jersey on Wednesday to determine whether they finish in the top two and progress to the Qualifier in Zimbabwe.
How to watch the Qualifier Play-off
The Cricket World Cup Qualifier Play-off will be available on Fancode in Afghanistan, Bangladesh, Bhutan, India, Nepal and Pakistan; and on Willow TV in the USA.
Fans in ALL other regions can watch the Qualifier Play-off live and FREE on ICC.tv on:
* ICC.tv website
* ICC.tv mobile apps (available in the App Store and Google Play)
* Samsung TV and LG TV apps
Cricket World Cup Qualifier Play-off
Watch Highlights of Every ODI as the USA and UAE Secured a Spot in the Next Stage - FREE on ICC.tv