[EGreg]

When people come to the US, they have to pay taxes on their income to the US cities, states and federal government. The cities and states can use this money to support our standard of living. Bringing people to our city is a vote for our standard of living.

Employing people overseas means we pay less, but the money goes out of the country. That means that, in the long run, we are voting against our standard of living and in favor of someone with a smaller cost of living than us, perhaps much less extensive social safety nets, etc. So in the long term, our workers' wages will be repressed in a race to the bottom with others. And our cities will have to cut their social programs to match whatever happens in the countries we outsource to. This occurs not just in the US but any countries with a high cost of living.

This is just mean reversion, and in the end of the day it's hard to fight against this. Things tend to equal out and the wages in the US will eventually approach the world average if the US stops being the main reserve currency of the world, and the dollar becomes weaker.

[tankenmate]

If the dollar becomes comparatively weaker then more people will probably be employed in the US (albeit at a lower relative wage) all things being equal. This is why countries like China work to keep their currency artificially low.