John Wesley Powell, explorer, geologist, and scientist, produced this map while he was the head of the Bureau of American Ethnology, as part of an 1890 Annual Report. According to Powell's description of the project, the map plotted "linguistic stocks of American Indians," as they were situated "at the time when the tribes composing them first became known to the European."
The map was a culmination of decades of work, Powell wrote in the section of the bureau's 1891 annual report that described its provenance. "The writer’s interest in linguistic work and the inception of a plan for a linguistic classification of Indian languages date back about 20 years, to a time when he was engaged in explorations in the West," Powell wrote (using the third person to refer to himself).
Being brought into contact with many tribes, it was possible to collect a large amount of original material. Subsequently, when the Bureau of Ethnology was organized, this store was largely increased through the labors of others. Since then a very large body of literature published in Indian languages has been accumulated, and a great number of vocabularies have been gathered by the Bureau's 26 assistants and by collaborators in various parts of the country.
In his description of the map, Powell exuded scholarly modesty: "[The map] is to be regarded as tentative, setting forth in visible form the results of investigation up to the present time, as a guide and aid to future effort." But the project was a big deal, writes historian Donald Worster in his biography of Powell: "The classification and map were Powell's most important achievement as bureau director ... and they set the standard for linguists well into the twentieth century."
The map was publicly displayed at the Chicago World's Fair in 1893, as part of a bigger exhibit mounted by the Bureau of Ethnology. Despite the amount of careful attention paid to Native culture and language, and despite Powell's own sympathetic view toward Native Americans, "no one viewing the exhibit would be troubled by any challenge to the notion that Indians in their native state were savages," Worster writes. "For all the complexity of their tongues, the bureau still insisted that the native peoples, before contact with the white man, had lived under hard material conditions and primitive superstitions and needed progress."
Click on the image below to reach a zoomable version, or visit the map's page on the Library of Congress website.