Part of Idaho is in the Intermontane Plateaus, mostly the Columbia Plateaus but a little in the southeast in the Basin and Range Province. The Rocky Mountains cut northwest to southeast across all four states. The Northern Rocky Mountains are in Idaho and Montana, with a tiny piece of northwest Wyoming. The taller Middle Rocky Mountains are in southwest Montana, southeast Idaho, northwestern and westernmost Wyoming and the northwest corner of Colorado. They rise above 4200 meters at Gannett Peak, Wyoming. The Southern Rocky Mountains are in south central Wyoming and across the center of Colorado. They reach almost 4400 meters at Mount Elbert, Colorado. Also within the Rocky Mountains is the Wyoming Basin in much of southern Wyoming and a little of north central Colorado. Eastern Montana, Wyoming and Colorado lie in the Great Plains, part of the Interior Plains. Several rivers originate in the Rockies. The Snake starts in northwest Wyoming and crosses southern Idaho before turning north along the the Oregon border. The headwaters of the Missouri arise just north of the Snake but head north into Montana; there it turns east and crosses the state. The Colorado arises in the high mountains of that state and heads west. The Arkansas starts south of the Colorado and heads in the opposite direction. The Rio Grande starts yet farther south and loops around before heading south out of Colorado.
These states are in the part of North America in which English-speakers and Christians are the majority.
The only very large city is Denver, Colorado's capital, sitting a mile high on the western edge of the Colorado Piedmont--part of the Great Plains--and right next to the towering Southern Rockies.
Salishan languages were spoken in northern Idaho and western Montana, as well as farther west and northwest. Secret societies were part of the local former religion. In the late 18th century smallpox, and in the early 19th century, influenza, reduced indiginous populutions in this area.
Uto-Aztecan languages are spoken in southern Idaho, southwestern Montana and western Wyoming. Northern Paiute still has a few thousand speakers in all states. Smallpox and cholera killed many in the first half of the 19th century.
Speakers of Algonquian languages such as Gros Ventre, Piegan, Cheyenne and Arapaho, occupied northern Montana east of the Rockies and eastern Wyoming.(1) Smallpox in the 19th century much reduced their original numbers. There are still about 2,000 speakers of Cheyenne.
Crow, a Siouan language was spoken in southern Montana. The Crow moved here from the east in the 1300's, the lands having been emptied in the century before.
English speaking Americans conquered the area, piece by piece during the 19th century.
north of Montana
northwest of Montana and north of Idaha
east of Montana and northeastern Wyoming
east of Colorado and southeastern Wyoming
southeast of Colorado
south of Colorado
west of Colorado, southwest of Wyoming and southeast of Idaho
southwest of Idaho
west of southern Idaho
west of northern Idaho
United States of America
North America
(1) Much of the Great Plains were depopulated in the 13th century. Algonquians, among others, moved in in the 14th century from the northeast and east.