First, a continental divide, usually a mountain range or other high ridge, which forms a separating line for the water flow on the continent, where all rainfall on each side of the divide flows to a different ocean or sea. Because these divides separate and determine the water flow patterns, they are also referred to as Water Divides.

The Red Desert occurs in Colorado in the extreme northwest corner of the state in the area where the continental divide has split to form a divide basin.

A divide basin is a geographic sub-features of the the continental divide which happens when the mountain range forming the continental divide separates and continues in two different directions with an open but lower area between. At some point, the two mountain ridges come back together and join to become one, thus forming the basin. This open lower area between the two ridges is in the form of a large bowl and remains part of the mountain range which forms the continental divide.

This bowl, or endorheic basin is one, by its nature allows, where none of the water falling as rain to the ground drains into any ocean, directly or indirectly, but converges instead into lakes or swamps, permanent or seasonal, that equilibrate through evaporation.

In the case with the Wyoming divide basin, there was once a large lake that filled the bottom of the basin and gradually because of the current drought has totally evaporated leaving only a dry hole.

The Red Desert is this endorheic basin and the basis spans across the three adjacent states, Colorado, Utah and Wyoming.