There have been a couple of things that have really crippled US exports.  Foremost among them has been that US companies (headquartered in Bermuda of course) started to source product from Chinese factories in the 1990's.  During the late 1990s this started to shift out of textiles and basic goods into things that had been value added goods.  I'm talking about aftermarket auto parts (auto parts not made for use in the auto industry but for repair by mechanics), consumer electronics, etc.  

Previously, much of this had been sourced from Mexico and Latin America. And Latin America has traditionally been one of the best markets for American export.  The Mexican economy has been under attack from cheap Chinese imports both internally and in it's exports to the US.

And I'll give my consent to any government that does not deny a man a living wage-Billy Bragg

is when Greenspan did nothing about "irrational exuberance" - ie the start of the dotcome bubble.

In the long run, we're all dead. John Maynard Keynes