ABSTRACT
Colorado is one of three western states—Colorado, Utah, and Wyoming—that can be described in this way. All of the other fifty states have some part or parts of their boundaries defined by natural features—seacoasts, rivers, the crests of mountain ranges, or lakes—but Colorado, Utah, and Wyoming have boundaries that conform to the geographic grid of latitude and longitude. The Rocky Mountains are a major component of the structural framework of the North American continent, sweeping up its western half from the Isthmus of Panama to the Arctic Ocean. The great irregular watershed created by the Rockies crosses into Colorado from Wyoming, advances southward in parallel ranges, swings westward in the great loop of the San Juans, and finally exits into New Mexico on a broad front. The geography of Colorado begins with its physical structure—its build—just as the frame of a building determines its eventual shape.
