Commerce was originally organized around the fur trade. Furs were carried by steamboat along the rivers to the settlements. Gold was discovered in the Black Hills in 1874 and attracted more settlers, setting off the last Sioux War. The population surge increased the demand for meat spurring expanded cattle ranching on the territory's vast open ranges. With the advent of the railroad agriculture intensified: wheat became the territory's main cash crop. Economic hardship hit the territory in the 1880s due to lower wheat prices and a drought.