Simply, the US manufacturing industry has taken a serious hit because of concerns over factory worker's income, health insurance, work environment, pension etc, these concerns will cost the company a lot to create their products.
So it's the norm to setup shop at a country who offers cheap labor due to their lack of concerns for factory workers
China is just as shytty, except they are doing it all over Africa.
http://www.dailymail.co.uk/news/art...ow-China-created-new-slave-empire-Africa.html
Mind you now China and the African Kingdoms are amongst the oldest trading partners in the World, but the Chinese are taking full advantage of Africa now; and in many cases the Chinese are bringing in Chinese workers to work on projects in Africa instead of hiring Africans. When they do hire Africans the Africans are getting the worst and most dangerous jobs; in some cases leading to the death of the African workers.
On a side note I still don't understand why African countries are not reaching out to African Americans to help them build their infrastructure. African Americans have the expertise and training to do many of the same things that the African nations are reaching out to have done.