1935 Map of Irwin

The presence of numerous remote outposts, including the Caribou Basin Ranger Sta and Brockman Ranger Sta, underscores the era's reliance on localized management of the backcountry. To the south, the expansive waters of Grays Lake are flanked by the Grays Lake Ranger Sta and Grays Lake Sch, marking a shift toward the high-altitude wetlands and basins. The map also preserves the location of Caribou City, providing a detailed look at the region's early mining and timber-based settlement pattern before later development altered these mountain valleys.