On 15 September 1858 transcontinental mail service between St. Louis, Missouri and San Francisco, CA began when the Overland Mail Company sent out its first stages. Under contract with the U.S. Postal Department, it would transport mail twice a week between those two points in 25 days. It avoided the slow ocean voyage and promised quicker transport of mail between east and west. Although subsidized by a $600,000 by the federal government, Overland Mail Company would spend over a million dollars establishing way stations (10-20 mile intervals) and improving the 2,800 mile route.

Custom-built stages driven by teams of horses soon were racing across the open spaces of the West. They carried more than mail with passengers willing to spend 25 days in carriage that was hardly comfortable. Way stations along the way provided some comfort but pricey. And if you got off the stage at a way station, there was a possibility the stage might take off with out you. In that case you were stranded until the next one arrived but if it was full it might be a while for the next one as well. Aside from the dust that was ever present, there were no comforts and the coach ran night and day. Toilets were few and far between (as were places to wash off the dust). Then there were other problems as well. Coaches were targets for robbers and even the occasional Indian attack making it sometimes a risky proposition. Add to it that some stage drivers were not always sober making the ride more uncomfortable. Some of the routes connected states like Alabama to California through Texas.

In 1860 Overland Mail was taken over by Wells Fargo that operated the Pony Express mail service and other operations. With the Civil War looming, the Overland would be forced to change its route by an Act of Congress. Its contract with the government would end in March 1861. During the war, many of the West and Southwest and stations would be become targets of either the Union or Confederacy to prevent their use by the other side. Wells Fargo would resume stagecoach transcontinental service but it would end on 10 May 1869 when the transcontinental railroad was completed. Local stagecoach service though would continue on (to ferry people, cargo, and mail away from trains) until the advent of the automobile. Today there is an effort underway to preserve the transcontinental route as a heritage trail.

Sources
1.This Day in History (History.com)
2. Butterfield Overland Mail Route (website about the mail route)