The New International Encyclopædia…
“ The rainfall in the south is very light, increasing toward the north and east, where the elevated ranges arrest the moist winds. Agriculture is thus limited to the mountain valleys and to the basins of the large rivers, such as the Salmon, Clearwater, Payette, and Boise, where irrigation can be practiced. These basins have a rich alluvial soil that produces excellent crops of cereals and fruits. The uplands have a moderately fertile soil of sands and clays, and are best adapted to grazing. ”
