The discovery of gold in 1858 brought an avalanche of prospectors. Some of these migrants later moved westward into the Rockies and Colorado River canyons. In 1873, another gold strike brought settlers into the Ute territory, eventually driving the Indians into a small reservation in the southwestern corner of the state. During the late 19th and early 20th centuries, the sparsely populated eastern plains were settled by farmers from Kansas and Nebraska and by immigrants from Scandinavia, Germany, and Russia. Five years of drought, from 1933 to 1938, helped drive many rural Coloradoans off the land into the cities or westward to California.
Since the end of World War II, net migration into the state has been substantial, amounting to over 880,000 between 1950 and 1990. Between 1990 and 1998, Colorado had net gains of 359,000 in domestic migration and 58,000 in international migration. In 1998, 6,513 foreign immigrants were admitted to the state. Growth has been evident in both urban and rural areas, but the largest increase has been in the Denver metropolitan area, where by 1997 14.3% of the total population were of Hispanic origin. A number of migrant workers, mostly Mexican Americans, work seasonally in the western orchards and fields. In the 1980s, migration accounted for 27% of the net population increase, with some 117,000 persons, even though there was a net loss from migration every year from 1986 to 1990. In 1990, native Coloradoans made up 43.3% of the population. Between 1990 and 1998, Colorado's overall population increased 20.5%. In the period 1995–2000, 643,820 people moved into the state and 481,187 moved out, for a net gain of 162,633.