Is it possible that Canada and the U.S.?
A couple of people have hinted at it but I will be blunt. Free entry/exit to Canada happens as soon as the US is satisfied that it can also happen with Mexico. For many reasons, including politics, we cannot treat Canada and Mexico differently. Of course Canada is an ally, supports the US internationally, after 9/11 had hundreds of thousands of its citizens holding vigils and helping stranded American travelers, and their PM who wasn't a huge USA guy was the first to call Bush and offer help and troops. Mexico of course did absolutely nothing per their typical nature. Seems like Canada deserves a more favorite nation status. I love Mexico and have worked there. But the country refusing to lift a finger after the US was attacked tells you what false amigos they are. Save me the casualties in the drug war. If you know Mexico it is more the factor of corruption and the refusal to allow open American assistance that has caused the toll. Colombia finally got serious and allowed US boots on the ground which subsequently took down a large part of the cartel threat (Jointly, many Colombians were involved.) If we treat Canada or Australia differently, fine by me. They have earned the right and trust.