If ONLY Americans have jobs, then you can ONLY sell "American Made" to Americans. EXPORT is critical in any economy, but if no one else in the world is working, who do you export to? If you set up a plant in Indiana the idea is to sell to Americans and to worldwide customers, but for that to work someone in Osaka Japan also needs to have a job in a plant there so he has buying power, and so on. So while home industry is critical, just as critical is industry abroad. Some guy in China, or Japan, or Germany or Canada needs a job just as badly as an American does. That's how global economy works. Isolationism doesn't work. It's been tried.