America's exceptional hat.

Seriously though, the big difference there is that Canada isn't nearly as racially diverse.

I don't think you mean racist.  I mean, American Exceptionalism is partially based on the fact that America has so many different races.  Which actually has been show to have a general positive effect when it comes to thinking "outside of the box", which is one reason why universitys actually try to be racially diverse.

As for the greatest thing since fire?

The Romans was a country that both had racism and diversity. Their mythical origin is like America's. It starts with a pilgremidge and ideally, a merging of the native and immigrating population.

The Romans were created as a result of Trojans and Latin people merging. The surrounding Latin states were considered non-Roman. Carthage, Gaul, Egypt, etc were considered barbarians. The later emperors of the empire, came from those areas, defending themselves from the Huns, Goths, etc. The Visigoths wanted to take refuge within the Roman empire, and if negotiations would have taken place, maybe there wouldn't have been a sack of Rome.

Those who were once slaves in Rome, became Freedmen, who then began to become the economic powerhouse of the state.

Fucking dark ages =/ If there only was gun powder, then cheap ass barbarians couldn't overwhelm civilized people with fucking horses.