Butterfield Overland Despatch
The Butterfield Overland Despatch was a mail and freight service operating across the Great Plains of America in the 1860s. Due to increased travel to Colorado after the discovery of gold in 1858, David A. Butterfield, backed by New York capital, organized a joint-stock express and passenger carrying service between the Missouri River and Denver.
Source: Wikipedia — Butterfield Overland Despatch (CC BY-SA 4.0)