From the plaque:
This was the site of the
western business headquarters of Russell, Majors, and
Waddell-founders, owners, and operators of the Pony Express,
1860-1861. The firm's main office was in Leavenworth,
Kansas, W. W. Finney was the western representative in
Plaque placed by the California State Park Commission in cooperation with the Society of California Pioneers, April 1, 1960.