Thirteen parks, the Rockies and the Colorado Plateau, and the best road trip in America.
This is the biggest region by park count and by visits, and it is the one that most clearly earns its shape. Utah's five, Colorado's four, Yellowstone and Grand Teton stacked on top of each other, Glacier at the Canadian border, and Great Basin out in the Nevada dark.
The connective tissue is elevation and the fact that these are all high-desert or high-alpine parks with a genuine season. Much of this region is snowed shut for months. Trail Ridge Road in Rocky Mountain and Going-to-the-Sun in Glacier both close in October and take crews weeks of plowing to reopen.
It is also the single most driveable cluster in the system. Zion to Bryce is 90 minutes. Arches to Canyonlands is half an hour. Grand Teton and Yellowstone share a border.
Zion and Bryce could sit in Desert Southwest on climate. We put them here on elevation and on the Utah trip everyone actually takes.