Cobbling shoes is an honorable occupation, but it's not rocket science. It requires only limited skill and technology, and the country with the lowest wage tends to get the business. That's why China sells so many sneakers to Americans, including David Clay, 42, a toolmaker who helps build humpbacked Boeing 747 aircraft in a giant hangar just north of Seattle.
What Clay and his co-workers do by contrast is rocket science. And even though seasoned machinists like Clay earn more in an hour (about $50, including fringe benefits) than a comparable Chinese worker is paid in a month, the American worker...