1943 Map of Commatti Canyon

About this map

The San Juan riverbed carves a wide path through the eastern San Luis Obispo County hills, defining a landscape of working ranches and secluded canyons during the early 1940s. Centered on Commatti Canyon, this topographic study reveals the dispersed settlement patterns of the era, where family-named holdings like Commatti Ranch, Alfalfa Ranch, and the E McCormack property anchored the local economy. The presence of the Alliance School near the junction of Tucker Canyon and Slocum Canyon indicates a established rural community even in this high-relief terrain. Survey markers from the U.S. Coast and Geodetic Survey, such as Cholame Tank and Red Hills, provide precise navigational anchors across the complex topography of McDonald Canyon and the Tin Can Canyon drainage, while locations like Sprague Camp and Alley Camp suggest seasonal or specialized land use in the backcountry.