From Canada to Mexico in Ninety Miles

Here's the single most remarkable thing about the drive you're taking — and almost nobody realizes it. In these ninety miles, from the high forested crest down to the desert floor at Clifton, you pass through very nearly every LIFE ZONE in North America: a sweep of climate and plants and animals that would take you thousands of miles to see if you drove the length of the continent. Up on top, the spruce, the fir, the aspen — those are the forests of CANADA. As we drop, we roll down through ponderosa pine, then piñon and juniper, then oak and grassland, and finally into the cactus, agave, and mesquite of the Sonoran DESERT — the country of MEXICO. A naturalist named C. Hart Merriam worked out this whole idea of 'life zones' right here in Arizona, on the San Francisco Peaks, and there is hardly a road on the planet that shows it off better than this one. So savor the descent: you are, in a single afternoon and one tank of gas, driving all the way from Canada to Mexico. Heads up through here: the road hairpins back on itself in tight switchbacks — take them slow, hug your lane, and use the pullouts to let anyone behind you go by.