Across southern Idaho, the I-84 freeway has effectively replaced the older highways, especially in the area southeast of Boise. The huge Mountain Home Air Force Base, 50 miles or so southeast of Boise, is the only thing for miles, which is no doubt by design: The base is home to the latest high-tech weapons systems and aircraft, whose pilots train at the adjacent, 110,000-acre desert bombing range.

Eighteen miles south of Mountain Home and the I-84 freeway via Hwy-51, Bruneau Dunes State Park (208/366-7919) protects one of the highest free-standing sand dune in North America—rising over 470 feet above the Snake River plain. Since the temperatures can hit 100°F throughout the summer months, mornings or sunsets are the best times to exercise your legs by climbing up and careening back down the white sands.