Final answer:
The Pony Express got its name because the mail carriers rode ponies to deliver the mail quickly.
Step-by-step explanation:
The origin of the name 'Pony Express' comes from the fact that the mail carriers rode ponies. The Pony Express was a mail delivery system that operated from April 1860 to October 1861 in the United States.
It was a fast and efficient way to transport mail across the country, using a network of riders who would ride on ponies to deliver the mail quickly.