“unlike years ago where we were the prime manufacturer of just about everything,”
True, but why? High US corporate income taxes hurt US manufacturing. Other countries tax their corporations less. Too powerful unions make the US manufacturing less competitive. Failure to US nuclear and other energy sources as we could, have denied us the cheap energy that would have fueled US manufacturing. Over-regulation, Obama-care, etc. have also reduced our competitiveness. It is currently illegal to export US oil, which is turning US booms to busts in energy production. Socialism is killing the economy in so many ways.
Trade improves our standard of living. That is why we do it. It works between individuals, counties, states, and between nations. In the 1950s we had trade and were very competitive. Today we take prosperity as a right and never give a thought as whether a proposed law will make us more or less competitive.
We were the prime manufacturers because our main competitors had suffered damage to some extent from WWII.
Trade may improve our standard of living by flooding our stores with cheap Red Chinese goods, but it is a double-edged sword - we will be looking at European-type unemployment levels for the foreseeable future, while we desperately traffick Third Worlders here to offset the steep drop in birthrate that accompanies such an economic malaise.