Who took tiny pieces of mail across the country over a hundred years ago?

Over a hundred years ago, the Pony Express was a service that took tiny pieces of mail across the country in the United States. Established in 1860, it relied on horseback riders to transport letters quickly between St. Joseph, Missouri, and Sacramento, California. The riders covered rough terrain and often faced dangerous conditions, but the service significantly reduced the time it took for mail to travel across the country. The Pony Express operated for only about 18 months before being replaced by the transcontinental telegraph.