It was deceptively difficult to have an "all USA-made" lightweight. If you wanted a three speed hub, the common option was the Sturmey Archer AW, even before WWII. New Departure had two and three speeds, but they were much less common on the lightweights than the AW. In the 1950s, it became even harder to have an all USA-made lightweight when Schwinn converted to Phillips and then Weinmann brake calipers and levers. The Weinmann parts were relatively inexpensive to source, lightweight, and pretty effective for their time. Eventually the Torrington spokes gave way to the Union spokes. And the chains became foreign-made.
Industry in the US certainly had the ability to make good bicycle components for lightweights, but it was often more profitable to use certain imported components on the lightweights.