Lost In Time

 Black and white photograph, no writing on reverse side.

Van reads:

• United States Army
• Medical Department
  U.S. Army

There's also a business sign in the background, I can't quite make it out. Seems like "CPEAD BAR."

Found in "Letters of a Self-Made Diplomat to His President" by Will Rogers. Published by Albert & Charles Boni, 1926.

Cleaned up close up:

-Click to enlarge photos-