The decimation of the price of unskilled labor via free trade was one of the all time Panglossian failures to consider second and third order effects.
It doesn't make low value-added goods like TVs, it doesn't employ a lot of people, and it's not growing as fast as other sectors, but we still manufacture more than ever before.
The “crumbling” sensation is because fewer people are employed by it and more people are employed (and earning more) in other sectors.
Yes, aerospace and military tech are the biggest manufacturing industries in USA... Quite profitable these days with all these conflicts...