The United States has never been anything like the "world's factory" the way China is. Before globalization kicked in hard first with Japan, then with China, manufacturing used to be a mostly local affair, with import being used only for very specific goods, not the entirety of all industries. To take as an example one of the industries that got destroyed the earliest by globalization, camera manufacturing, there were plenty of European countries competing with each other in the field, with eastern European focusing on cheap, often flimsy (but with decent gems here and there) cameras, and western Europe making the more high end stuff. Even smaller industrial countries like France used to make its own cameras. and some amazing optics. Now the only thing that is still built in Europe is luxury goods (Leica) but even a luxury brand like Leica still make most of its components in the cheapest of all Euro countries: Portugal. So japan came in, and became the world's monopoly on camera manufacturing by making cheap knockoff of European stuff. European brands died and the Japanese ended growing their industry enough to fund their own R&D. Now they make most of their stuff in China (except for Pro gear), with R&D in Japan. Europe, Russia and the United States used to have healthy camera industries, now we're all buying Japanese stuff made in China. But that's just one tiny example of all industries that were lost and that used to be diverse, diverse in that many, many countries were competing and had their own local industries.

Japan and China literally screwed the rest of the world. Not just the United States.