That's a pretty ignorant article. The limiting factor for immigration is how quickly you can Americanize immigrants, not land area.
As for why it's imperative to Americanize immigrants. Look at how much trouble the U.S. has had cultivating democracy in places like Iraq. Most people acknowledge that the Iraqi people aren't ready for Democracy. Do you think they would be any more ready for democracy if you moved them en masse to Minnesota?
As for why it's imperative to Americanize immigrants. Look at how much trouble the U.S. has had cultivating democracy in places like Iraq. Most people acknowledge that the Iraqi people aren't ready for Democracy. Do you think they would be any more ready for democracy if you moved them en masse to Minnesota?