HD 447 covers the Centennial Valley and the surrounding ranges along the Idaho border in southwest Montana—one of the most remote, beautiful, and least-visited corners of the state. Elevations run from about 6,500 feet on the Centennial Valley floor to over 9,000 feet on the Centennial Range divide and the Snowcrest Range to the north. The Centennial Valley itself is a broad, high sagebrush basin with extensive willow-lined creek bottoms, the Red Rock Lakes (the headwaters of the Missouri), and Red Rock Lakes National Wildlife Refuge—one of the most important breeding habitats for trumpeter swans in the lower 48. The Centennial Range walls the south side along the Idaho border with timbered slopes climbing through Douglas fir, lodgepole, and spruce-fir to the divide. The Snowcrest Range to the north is similar high rolling country. Elk and pronghorn are the headline species; mule deer in the timbered slopes; moose in the willow bottoms; some bighorn sheep on rocky outcrops. Red Rock Lakes NWR provides the bulk of the public access in the valley itself (refuge regs apply—check the specific rules for big-game hunting), with Beaverhead-Deerlodge NF on the surrounding high country, BLM on lower benches, and significant private ranches (the Centennial Valley ranches are some of the largest working cattle outfits in MT). The valley is reached by MT-509 from Monida (off I-15) or by the back-road approach from Lakeview—both are dirt and require dry weather to be reliable. Lakeview is essentially a research-station compound, not a town. Lima on I-15 has gas and a cafe; Dillon is the real supply hub. Cell service is gone in the valley. This is genuinely remote country—plan accordingly with extra fuel, food, and patience for changing weather.