Canada seems to be going in the opposite direction lately. If there's going to be a merger expect it to be between the US and Mexico. We have very little historical ties to that country other than being a neighbor but there's just too much cheap labor down there for the big corporations to ignore. And they have lots of oil.
This is not the exact article because the one I saw gives dates specific of an agreement but this one is similar. I am sure you probably have seen it. Couple this with the Trilateral Commission and I fear we are doomed.
"March 14, 2005 - Three former high-ranking government officials from Canada, Mexico, and the United States are calling for a North American economic and security community by 2010 to address shared security threats, challenges to competitiveness, and interest in broad-based development across the three countries." Quote from below link.
http://cfr.org/publication/7914/trinational_call_for_a_north_american_economic_and_security_community_by_2010.html
If you read this and then the other link it is a pretty sure thing as far as I am concerned.