The Great Basin has few rivers because it is an endorheic basin, meaning it has no outflow to the ocean.

The Great Basin's unique geography as an endorheic basin means that water within the region does not flow out to the ocean. Instead, rivers and streams either evaporate or drain into isolated lakes and salt flats, with no outlet to the sea. This absence of outflow is the primary reason for the lack of rivers in the region. The water that does enter the basin remains within, contributing to the formation of salt flats like the Great Salt Lake. This distinct hydrological system shapes the environment of the Great Basin, making it a dry and arid region.