Poster from the Pony Express: American History

The Pony Express was a mail service delivering messages, newspapers, mail, and small packages from St. Joseph, Missouri, across the Great Plains, over the Rocky Mountains and the Sierra Nevada to Sacramento, California, by horseback, using a series of relay stations. During its 18 months of operation, it reduced the time for messages to travel between the Atlantic and Pacific coasts to about 10 days. From April 3, 1860, to October 1861, it became the West's most direct means of east–west communication before the telegraph was established and was vital for tying the new state of California with the rest of the country. [via Wikipedia]