1941 Map of Swarthout

About this map

The San Andreas Rift Zone creates a striking geological corridor through this portion of the San Gabriel Mountains as surveyed in the mid-1930s. This high-altitude landscape is characterized by a concentrated recreational and administrative infrastructure within the San Gabriel National Forest, featuring the sprawling Big Pines Camp Area and the Smithsonian Observatory atop Table Mountain. Transportation routes like the Pear Blossom Highway and the uniquely named Tennis Courts Highway connect various mountain retreats, including Camp McClellan and Junior Republic Camp. The map provides an intricate look at the headwaters of the Prairie Fork and Fish Fork, where isolated outposts like the Prairie Fork Guard Sta and Cabin Flat served as remote landmarks for forest management and early mountain travelers.