From the plaque:
This was the site of a change
station of the Pioneer Stage Company in the 1850s and
1860s. During 1860-1861, the Central Overland Pony Express
maintained the first pony remount station east of Sportsman's
Plaque placed by the California State Park Commission in cooperation with the James W. Marshall Chapter No. 49, E Clampus Vitus, and the Central Overland Pony Express Trail Association, April 30, 1960.