The species is native to the central part of the United States, from Missouri to Nebraska, to Colorado, south to Texas, and into northern Mexico.

The epithet, emoryi, is in honor of Brigadier General William Hemsley Emory, who was chief surveyor of the U.S. Boundary Survey team of 1852 and collected specimens for the Smithsonian Institution.

It can often be found on farmland, which often leads to its being erroneously called a chicken snake, and other areas with a relatively high rodent population, which is its primary diet.

The Great Plains rat snake tends to remain still for a majority of its time awake, which is odd for a nocturnal being.

This study illustrates the importance of thorough sampling of contact zones and consideration of gene flow when delimiting species in widespread complexes containing parapatric lineages.