[jogjayr]

Something worth pointing out here: apart from the EU, there isn't even open immigration among rich countries. A Swede, (or Briton or Canadian) can't just decide to pack his things up and come to work in the US (though the visa waiver program for tourists is pretty sweet). There are still visa hoops to jump through, paperwork to be done. It's easier, if you're a rich-country-citizen, to move to another rich country, but by no means a done deal.

It's hard to make a logical argument that immigration controls exist purely for economic reasons; social services and weather apart, Sweden (or the UK or Canada) and the US have comparable standards of living and levels of English proficiency. None of the arguments against allowing unchecked immigration from poor countries to rich (education, overwhelming public services, falling wages etc) apply in this scenario and yet (again, apart from the EU), open immigration between roughly equally developed countries doesn't exist.