Photo of Barbara Wall, a World's Fair guide by David E. Scherman for LIFE, 1939.

The 1939/1940 World's Fair was attended by 40 million people including Albert Einstein and F.D.R., and according to Popular Mechanics featured futuristic devices like Elektro the Motoman and transatlantic travel via "rocketgun" and, ok, television. But also featured at the fair were "girl guides"—hired for their enthusiastic attitude and encyclopedic knowledge. They earned $25 a week and walked 15 miles per day.