About the Pony Express
The Pony Express was founded by William H. Russell, William B. Waddell, and Alexander Majors all three who were stagecoach riders before they took on creating the Pony Express. The Pony Express was created shortly before the start of the Civil War because people needed news faster about the threat of a war. The Pony Express was also created because of the Gold Rush. More people moved out west and therefore, more people needed mail from the east. The benefit was that instead of the usual 20 days that it took for mail to travel from St. Joseph, Missouri to Sacramento, California, after the creation of the Pony Express, it took an unprecedented 10 days. Overall, the entire trip was 1,600 miles and the riders rode on what is now known as the Pony Express National Historic Trail.
Horses, or Broncos were chosen and bought based on fleetness, toughness and endurance; overall, 600 broncos were purchased. Furthermore, 75 men were hired to ride the horses across the country; none weighed over one hundred and ten pounds. Although they had a strict weight requirement, the men were also chosen based upon their bravery, riding skills, shooting abilities and their knowledge of craft when it came to dealing with the Native Americans.
The first westbound trip was made in 9 days and 23 hours and the eastbound journey in 11 days and 12 hours. The pony riders covered 250 miles in a 24-hour day. As the Pony Express got more established, a rider would leave St. Joseph everyday at noon, while another rider would leave Sacramento at 8 o’clock in the morning, except on Sundays. There were 100 stations along the way that riders could stop at to change horses or get something to eat. For two years, or more specifically 19 months; the pony express was used to get letters from Missouri to Sacramento. The cost of carrying the letter was 5 dollars. Ten weeks after the start of the Pony Express, Congress passed a bill in which started the construction of telegraph lines to the west. Therefore, after the telegraph finally reaching California, there was no longer a need for the Pony Express and therefore, it was over. The first mail to reach California was on April 13, 1860 and in its two year span, only one mail delivery was ever lost.

http://www.sfmuseum.org/hist1/pxpress.html
http://www.ponyexpress.org/index.php?page=History
http://www.nps.gov/poex/historyculture/index.htm