Before 1860, sending mail between the eastern and western United States was very slow. It could take weeks to months. So a man named William Russell started a faster mail service. It was called the Pony Express.
The Pony Express started in April 1860. Young men were hired to carry mail. They did this by riding horses. Each rider rode about 75 to 100 miles. Then he gave the mail to a Pony Express worker or another rider. Some riders had to ride through dangerous places.
A lot of mail was sent using the Pony Express. In the summer, it delivered mail in about 10 days. In the winter, it could take up to 16 days.
About 18 months after it started, the Pony Express stopped its service. Why? In October 1861, the first telegraph system between the east and west was completed. It could send messages in just a few hours by wire.