Have you heard of the Amero? This is a hypothesized future currency that would merge the US Dollar, Canadian Dollar and the an equal Mexican equivalent that is not currently in existence.
The concept of merging currencies to compete with the EU and Euro is a dream of many in North America.
   It would indeed, foster trade and make business with our neighbors that much easier.
Of course, considering the issues of our day; the economic crisis, the Mexican drug wars and current state of affairs, that goal is a ways off.
   Indeed, it appears that it may not be feasible for quite a while - let's say 20-30 years or more.
Our next door neighbor in Mexico is a third world country and almost turned communist this last go around (presidential elections), then the tortilla riots ensued, that was a hoot, until you consider the reality of it all.
The presidential candidate that lost by the narrowest of margins was a communist leaning politician.
   Mexico has way too far to come up to merge, too much corruption, it's unworkable in the present period, for us to merge currencies now.
Canadian Dollar has dipped too, 78% of a USD now, and we still have some differences to work out, including as President Obama stated; re-negotiating NAFTA.
  But, all this does not make it possible and one day, we may actually see a merging of the minds and currencies in North America.
Will it be in our lifetimes? Perhaps, although perhaps not.
That's my take on it.
Think on this.