Which route represents a journey from a plains region to a mountains region?

The journey from St. Louis to Denver represents a transition from a plains region to a mountainous area. St. Louis is situated in the Mississippi River basin, which is characterized by flat plains and gentle terrain, while Denver lies at the foot of the Rocky Mountains. This route signifies a significant change in elevation and landscape, as travelers move from the relatively flat Midwestern plains into the more rugged terrain of the mountains.

In contrast, other routes do not exhibit the same geographical transition. For example, traveling from Houston to Austin remains within the flat coastal plains of Texas, and a journey from Chicago to Seattle crosses various landscapes, including plains and hills, but does not specifically focus on moving from plains to mountainous regions. Omaha to Salt Lake City also involves a varied terrain, but it doesn’t represent the same clear shift from a specifically defined plains region to a mountain area as seen in the St. Louis to Denver route.