Not exactly true.....
From the New Balance website, you can do your own interpretation of what this really means:
We are proud to be the only major company to make or assemble more than 4 million pairs of athletic footwear per year in the USA, which represents a limited portion of our US sales. Where the domestic value is at least 70%, we label our shoes Made in the USA.
And also:
In the 2020 annual report, New Balance says, “We outsource the production of our products to independent manufacturers, which are primarily located in Asia.”
As usual, buyer beware and don't believe all the marketing hype.