But where are the best short drives?
For instance, the 16-mile drive from Madison Junction in Yellowstone National Park to the Old Faithful area takes you past some spectacular thermal features -- Fountain Flat Drive, Firehole Lake Drive with the short hike to Fountain Paint Pots, the Midway Geyser Basin with Grand Prismatic Spring, Biscuit Basin, Black Sand Basin. And drifting through it all is the Firehole River.
The short ride on a portion of the Park Loop Road (aka Ocean Drive) in Acadia National Park from Bar Harbor to Otter Cliff takes in the trailhead to the Precipice Trail, leads to Sand Beach and the trail to the Beehive, and Thunder Hole. And all along the way you've got beautiful views of the Atlantic Ocean.
And, of course, the 18-mile Rim Road at Bryce Canyon National Park shows off the colorful underbelly of the Paunsaugunt Plateau.
So, where are the best rides, no longer than 20 miles one-way, in the National Park System?