[mitthrowaway2]

On a per-capita basis that's not hugely different, but one of the reasons may be that Canada provides a somewhat easier path, relative to the United States, to becoming a legal immigrant rather than remaining undocumented.

[lazide]

Really? I’ve had relatives try to immigrate to Canada (from the US), and it was quite a horror story. Any specifics?

[nemo]

Relative to Canada the United States is even more difficult to legally immigrate to, consider that the US system has been constantly adding ever increasing hurdles to legal immigration for ages.