From the March 17, 2016, Shorpy Photos.
You can go to the site and see the picture.
"We are signing the Victory Highway, San Francisco to New York."
San Francisco, circa 1921, "White motor truck at Palace of Fine Arts--California State Automobile Association."
A project from the early days of long-distance motor travel, when auto clubs took the lead in establishing and marking routes between cities and across the country.
A sign on the truck reads: "California State Automobile Ass'n" There is also a picture of Yosmite Valley, California painted on it and the words "We Are Signing."