When the first national parks were established in the late 1800s, Americans began to develop a greater appreciation for the natural beauty in their backyard. The arrival of cars made it easier to access them – although it was still a privilege available to the wealthy few who were lucky enough to own one. Pictured here is a group of visitors on a guided 'Two National Parks in Two Weeks' tour that swept through Rocky Mountain National Park and Yellowstone National Park.

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Nostalgic images of American road trips from every decade