The Pony Express was an American express mail service that used relays of horse-mounted riders between Missouri and California. It was operated by the Central Overland California and Pikes Peak Express Company.
During its 18 months of operation beginning in 1860, the Pony Express reduced the time for messages to travel between the east and west US coast to about 10 days. It became the west's most direct means of east–west communication before the first transcontinental telegraph was established (October 24, 1861), and was vital for tying the new state of California with the rest of the United States.
Despite a heavy subsidy, the Pony Express was not a financial success and went bankrupt in 18 months, when a faster telegraph service was established.