When the dog days of summer set in, many people respond by taking to the hills to cool off. Arizona is particularly prone to this type of behavior. Like migrating birds, Arizonans flood the highways on Friday afternoons in summer, streaming north to Flagstaff, Payson, Prescott and other high-altitude retreats. The cool pines of the high country lie only a few hours from the sweltering heat of Phoenix. Farther south in Tucson, seven-thousand foot tall mountains sit just outside the low, desert city. Escaping the heat is a matter of driving up the mountain, which only takes about half an hour.