http://www.nps.gov/parks.html A nice website which shows all the UnitedStates National Parks.
I guess there are differences between a NationalPark and a NationalMonument, but I suppose it's a class difference. NationalPark is a superclass of NationalMonument??
Such as...
* MountRushmore
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Please, folks, watch out for AmericanCulturalAssumption.