The design is a playful thought on the dichotomy between nature and the urban environment.
We all like to escape the hustle and bustle of the cities, and be re-created in the Great American Outdoors. But, we insist on getting there individually and 'free' by driving our SUV's, trucks and 4WD cars. In the peak season, the parks are facing vast traffic and parking problems. Maybe that's the reason why the bison in the NPS logo usually looks so dull...