There’s an interesting article on #AppleInsider about why Apple won’t be manufacturing iPhones in the US any time soon. Aside from the big difference in labour costs between the US and China, there’s this:
“Vocational training is not seen as taking the "lower path" in China, while many other countries have de-emphasized vocational trades. Because these trades are still considered worthwhile, China has a wealth of tooling engineers.”
AppleInsiderUS iPhone production's main challenge is a century of big business labor decisionsDespite repeated political promises recently saying otherwise, because of federal wants and big business needs over the last 100 years, the U.S. lacks both the low-cost labor and specialized manufacturing workforce needed to bring iPhone production home.
Mechanic 
Daron Brewood