Government and private enterprise sent many explorers to the West. In 1805–1806, Army lieutenant Zebulon Pike (1779–1813) led a party of 20 soldiers to find the headwaters of the Mississippi. He later explored the Red and Arkansas Rivers in Spanish territory, eventually reaching the Rio Grande. On his return, Pike sighted the peak in Colorado named after him. Major Stephen Harriman Long (1784–1864) led the Yellowstone and Missouri expeditions of 1819–1820, but his categorizing in 1823 of the Great Plains as arid and useless led to the region getting a bad reputation as the "Great American Desert", which discouraged settlement in that area for several decades.