China isn't the biggest threat to American/Canadian Labour

It's (the lack of) productivity (NYT via Instapundit):

Now, companies that want to make things here often have trouble finding qualified workers for specialized jobs and American-made components for their products. And politicians’ promises that American manufacturing means an abundance of new jobs is complicated — yes, it means jobs, but on nowhere near the scale there was before, because machines have replaced humans at almost every point in the production process.

Take Parkdale: The mill here produces 2.5 million pounds of yarn a week with about 140 workers. In 1980, that production level would have required more than 2,000 people.