Specializations change over time. The US, specifically Silicon Valley, has different specializations today than it did in the 60's. A lot of the semiconductor specialization moved overseas, costs came down, and in general the world is richer. Other specializations include things like China and injection molding, Japan and mechatronic technologies in the 80's and 90's, Thailand and lenses, etc
Obviously the protectionist crowd would take issue with all this, but free trade theory is studied and applied all over in trade agreements, specialization zones (like Shenzen), etc. Generally speaking though, the cost of attempting to be self sufficient in everything (like semiconductor manufacturing) means closing borders to competitors outside, which eventually leads to inferior product. With robust competition, the consumer usually wins on both quality and price. Obviously there are other consequences, such as job migration etc. In general though, everyone is lifted up and made richer over time (evident by the fact that there is quantitatively less poverty in the world today and the 1960's and even the most poor can enjoy things like cellphones, leather jackets, and shoes that fit well that even the kings of a century ago could not). The system isn't perfect, but atleast in my eyes it is the one that does the most good for the most people.