(1877 - 1887).
In the late eighteenth century, reformers starting with Washington and Knox,supported educating native children, in efforts to "civilize" or otherwise assimilate Native Americans to the larger society (as opposed to relegating them to reservations). The Civilization Fund Act of 1819 promoted this civilization policy by providing funding to societies (mostly religious) who worked on Native American improvement.
After the American Civil War and Indian wars in the late 19th century, Native American boarding schools were established, which were often run primarily by or affiliated with Christian missionaries. At this time American society thought that Indian children needed to be acculturated to the general society. The boarding school experience often proved traumatic to Native American children, who were forbidden to speak their native languages, taught Christianity and denied the right to practice their native religions, and in numerous other ways forced to abandon their Native American identities and adopt European-American culture. There were documented cases of sexual, physical and mental abuse occurring at these schools.
In his highly influential Frontier Thesis in 1893, Frederick Jackson Turner concluded that the frontier was all but gone. (But with the discovery of gold in the Klondike in 1896, a new frontier was opened up in the vast northern territory. Alaska became known as "the last frontier."). After the eleventh U.S. Census was taken in 1890, the superintendent announced that there was no longer a clear line of advancing settlement, and hence no longer a frontier in the continental United States. The West was finally conquered, achieving Manifest Destiny, in less than one hundred years after the frontier breached the Mississippi River. By century's end, the population of the West had reached an average of two people per square mile, which was enough to be considered "settled". Towns and cities began to grow around industrial centers, transportation hubs, and farming areas. In 1880, San Francisco dwarfed all other Western cities with a population of nearly 250,000. Over opposition from mining and timber interests, the federal government began to take steps to preserve and manage the remaining public land and resources, hence exercising more control over the affairs of Westerners.