I can't find hard data on this, but anecdotally it's very hard to find things made in the US unless it's a high end store. Chinese manufacturing filled the burst in consumer demand for budget-level products...
manufacturing output is measured in dollars, not 'amount of stuff' except in very specific cases. producing fewer but more expensive high end goods (like what the US makes) can still result in more output.
The US manufactures a lot more high value items where as China dominates the cheap junk category. Same way that Apple has all the smart phone profits even though they don't dominate the smart phone market on a number of units sold basis.
http://www.economist.com/blogs/theworldin2011/2010/12/china_...
Competitiveness is the thing that has (for example) Apple making things in China.