Ok, is Europe one country? or is there many countries in Europe? Then why did not the Europeans formalize one country like America? Again the same question is Asia one country? Also why did not North American expands throughout the Americas example Canada, Mexico, or all the way to Argentina since they occupy the same continent? That will include the Caribbean as well since America has possession of few of the islands within the Caribbean. (example Virgin Islands and Puerto Rico) Why not expand the Pax America, similar to the Roman Empire? Since it again occupy the same space or Continent. Most countries in the world don't consider North and South America as separate continents. People generally believe that the Americas is one continent.
Americas
Europeans didn't have a common enemy, they were their own enemies.