What metaphors are used in This House of Sky: Landscapes of a Western Mind by Ivan Doig?

The state of Montana becomes a metaphor of the white American settler psyche. In this case, the entire massive place is meant, all of a piece. This vast terrain has some variation, but is predominately grasslands. This land was claimed by the white man, and by the American government in the 1800s. There were concerted efforts to have it settled: homesteads were offered.

Homesteaders entered the region in the 1870s. The going was quite tough, actually. Within 50 years the conclusion was made that it was usable as ranch land, but not everyone could manage that.