Stephen Harriman Long was an American army civil engineer, explorer, and inventor. As an inventor, he is noted for his developments in the design of steam locomotives. He was also one of the most prolific explorers of the early 1800s, although his career as an explorer was relatively short-lived. He covered over 26,000 miles in five expeditions, including a scientific expedition in the Great Plains area, which he famously confirmed as a "Great Desert".

The term Great American Desert was used in the 19th century to describe the part of North America east of the Rocky Mountains to approximately the 100th meridian. It can be traced to Stephen H. Long's 1820 scientific expedition which put the Great American Desert on the map.