2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 10/ 



The Missouri River Basin comprises a territory of nearly 530,000 

 square miles — ^approximately one-sixth the area of the continental 

 United States. It extends about 1,350 miles from Glacier National 

 Park, Mont., in the northwest to St. Louis, Mo., in the southeast, and 

 more than 700 miles from Colorado's South Park in the southwest to 

 Devils Lake, N. D., in the northeast. The Missouri River itself, from 

 its source at Three Forks, Mont., flows 2,500 miles in a general 

 easterly and southerly direction through or along seven States. With 

 its innumerable tributaries, it drains all of the State of Nebraska, por- 

 tions of the States of Montana, Wyoming, Colorado, North Dakota, 

 South Dakota, Kansas, Minnesota, Iowa, and Missouri, and small 

 areas in the Canadian provinces of Alberta and Saskatchewan. 



There is no need here to dwell on the wide diversity of terrain, 

 climate, native fauna and flora, and other environmental aspects of 

 this vast region. Briefly, the Basin rises in altitude from about 400 

 feet above sea level at the mouth of the Missouri to the 10,000- to 

 14,000-foot snow-capped summits of the Continental Divide in Mon- 

 tana and Colorado. The watershed consists largely of plains, but in 

 south-central Missouri, in western South Dakota, along the easterly 

 slopes of the Rockies, and elsewhere there are rugged areas of con- 

 siderable extent. Annual precipitation ranges from 40 inches at the 

 mouth of the Missouri to less than 10 inches in parts of Wyoming and 

 Montana. East and north of the Missouri River the soils are mainly 

 of glacial origin ; to the west and south residual, alluvial, and sandy 

 aeolian soils predominate. Native vegetation consists of oak-hickory 

 hardwood forests in the extreme southeast, successively replaced 

 toward the west by tall-grass prairie, short-grass plains, the sagebrush 

 and desert scrub of Wyoming, and finally the western pine forests of 

 the Rocky Mountains. Like the region, its ethnography and its ar- 

 cheological remains also show marked and significant variation from 

 one section to another. 



In the historic period, that is, since approximately 1775, the Mis- 

 souri River watershed has been inhabited by numerous Indian tribes 

 of varied linguistic affiliations and diverse cultural practices. Some 

 were demonstrably late arrivals ; others had apparently been long resi- 

 dent in the area when first recorded by white visitors. In the semiarid 

 grasslands of the western plains and along the base of the Rockies 

 roamed several tribes who may be collectively termed the migratory 

 bison hunters. In north-central Montana, north of Musselshell River 

 and west of the mouth of Milk River, were the Blackfoot and Gros 

 Ventres, with the Assiniboin to the east. On the Yellowstone River 

 and its southerly branches in southeastern Montana and northeastern 



