For how long did the Pony Express service operate in the United States?

On 3 April 1860, a pair of riders left their respective starting points of St. Joseph, Missouri, and Sacramento, California, with the goal of delivering a backpack of mail to the other city within 10 days. The route stretched across the Midwestern plains and Western deserts and mountains, the riders stopping for fresh horses every 10 to 15 miles before handing off to another rider after a few stops. The mailbags reached their destinations on 14 April just missing the 10-day goal but fast enough to show that the Pony Express, could deliver mail at a speed that bested existing services by weeks.

The Pony Express -- officially the Central Overland California & Pikes Peak Express Company, was founded by businessmen William Russell, William Waddell, and Alexander Majors, who hoped to secure an exclusive mail contract from the federal government with their new service. For a while they succeeded, despite expensive rates and the disruption caused by various conflicts between Indigenous peoples and settlers.

The Pony Express had a short life – just 18 months. The telegraph already ran from the East Coast to the Mississippi River by April 1860 and, two months later, Congress had authorised the subsidisation of a coast-to-coast telegraph system. The completion of the transcontinental telegraph line in October 1861 marked the official demise of the Pony Express.