The One Minute Geographer: The Great Plains — High Plains and Low Plains

The Great Plains in blue with the 100-degree longitude line. Map from Wikipedia; line drawn by the author.

More about the 100-degree meridian. It runs through the heart of the Great Plains as you can see above. Definitions of the boundaries of the Great Plains vary and not all include Iowa and the sections of Minnesota and Missouri shown on this map.

The Magical Meridian also tends to lie near a break in elevation on the Plains. Very generally, this meridian follows a line marking the 2,000-foot line as elevation increases to the west, heading toward the Rockies. The map below shows this distinction between the High Plains and the Low Plains.

High Plains and Low Plains on this historical map showing what used to be called the Great American Desert. Map from historyonthenet.com; meridian drawn by the author.

West of this line of elevation lies the area called the ‘High Plains’ in almost all states. To the east, the hillier, more eroded sections of the Low Plains are given various names. In Kansas for example the Low Plains are called the Smoky Hills, Flint Hills and Red Hills; in Oklahoma, the Gypsum Hills, and in Texas, the North Central Plains.

In the southern part of the Great Plains, especially in Texas, the break between the High and Low Plains is sharp, as shown in the picture of the Caprock Escarpment, about 80 miles west of the meridian.