>>It's so obvious that it seems to go unrecognized sometimes that geography is part of the issue. There have always been richer nations and poorer ones. I don't think there has ever been a case of a rich nation and a poor one sharing a 1000 mile border. When wages and the standard of living are so much higher on one side of a somewhat imaginary line, should we be surprised that people cross the border in large numbers? I realize there are some who consider those who cross the border to be criminals, but it's really just human nature. I don't blame anyone for wanting better lives for themselves and their children. Especially when it's close enough to see with your own eyes. You don't have to get on a boat and sail across the ocean.
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>OTOH, every border is as penetrable as the counties it divides want. Every country has borders, they pretty much define it. The ratio between the border length and the population, i.e. how many miles of border per capita can't vary that much. In that respect, I figure Canada would fare the worst.
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>So how come so many other countries don't have such problems?


Because there isn't such a disparity in the standard of living.