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 mi (81 km) 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 (44,500 hectares) desert bombing range.
Bruneau Dunes State Park
Bruneau Dunes State Park (208/366-7919), 18 mi (29 km) south of Mountain Home and the I-84 freeway via Hwy-51, protects one of the highest free-standing sand dune in North America—rising over 470 ft (143 m) above the Snake River plain. Since the temperatures can hit 100°F (38°C) 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.
The tiny town of Glenns Ferry, 28 mi (45 km) southeast of Mountain Home on the Snake River and I-84, would hardly rate a mention were it not the site of one of the most important crossings on the old Oregon Trail. This site, now preserved as Three Island Crossing State Park ($5 per vehicle), a mile (1.6 km) southwest of town, gives one of the strongest impressions of the tough going for Oregon-bound pioneers. A good visitors center (208/366-2394, Memorial Day-Labor Day Tues.-Sat.), with a Conestoga wagon out front, has displays of trail lore and history. Go for a swim to cool off and feel the powerful currents—more placid here than most anywhere else, which is why it was considered the best place to ford the river. This is also a fine place to camp; the usually clear night sky makes for excellent stargazing.