From Why Apple’s products are ‘Designed in California’ but ‘Assembled in China’ | TUAW - The Unofficial Apple Weblog:
The Chinese factory where most iPhones reach final assembly employs 230,000 workers. I just asked Siri how many cities in the US have a population higher than that, and the answer was a mere 83 cities — and that’s total population, not workforce. With an average labor force of around 65 percent of the population, only 50 US cities are large enough to provide that kind of labor pool… and even in the biggest US city of them all, New York, 230,000 people still amounts to almost three percent of the city’s entire population. Can you imagine three out of every hundred New Yorkers on an assembly line, cranking out iPhones every day?</blockquote>