How old was William "Buffalo Bill" Cody when he signed up to work with the Pony Express?

Answer: 14 Years Old

History - Among the riders was the legendary frontiersman and showman William “Buffalo Bill” Cody (1846-1917), who reportedly signed on with the Pony Express at age 14. 

Born in Iowa in 1846, Buffalo Bill Cody began working for the Pony Express when he was just a teenager. He fought in the Civil War, served as a scout for the Army, and an actor who traveled the United States and Europe.

While Cody was serving in the American Civil War he began hunting buffalo to feed construction crews building railroads. This is what lead to his infamous nickname.