Where is the Western Worm Snake, *Carphophis vermis*, generally geographically distributed relative to the Mississippi River?

Generally located west of the Mississippi River valley, including states like Nebraska

The genus *Carphophis* is represented by two species whose primary separation mechanism is geography, illustrating speciation driven by isolation. The Eastern Worm Snake, *Carphophis amoenus*, dominates the eastern half of the United States distribution. Conversely, the Western Worm Snake, *Carphophis vermis*, occupies a distinctly separate range. This western range is typically defined as being situated generally west of the Mississippi River valley. States such as Nebraska fall within this domain. This geographic partitioning has resulted in reproductive isolation and measurable genetic and subtle morphological differences, justifying their status as separate species despite their similar body plans.