Two days after the Transcontinental Telegraph reached Salt Lake City, on October 26th 1861 the Pony Express ended its run.
The Pony Express was founded by William H Russell, William B Waddell and Alexander Majors. It began moving the mail from ST Joseph Missouri to Sacramento California on April 3rd 1860. This mail service which operated for only 18 months; carried the mail on horseback across country in about ten days. From March 1861 the Pony Express only moved mail between Salt Lake City Utah and Sacramento. Once the telegraph reached Salt Lake City, it connected Sacramento with Omaha Nebraska, and the Pony Express stopped moving mail on October 26th 1861. The Pony Express lost over $200,000 while in operation. After the end of the Civil War in 1866 the assets of the Pony Express and the Butterfield Stage Company were sold to Wells Fargo for $1.5 million.
Other good web site for more information
Gold Rush Chronicles, The Pony Express
Pony Express History