I've read that Greece's original application for joining the euro was a complete fraud and they were in no way close to meeting the fiscal requirements to join. That should serve as a warning for any who want to form a North American monetary union. Both the United States and Canada could be harmed by fiscally irresponsible neighbors to the south.
To the South? Fiscally irresponsible neighbors for me in Pennsylvania are to the South in Washington, DC, and to the North in Harrisburg.