The Agricultural Core

This region has some strong similarities with the area immediately surrounding Boulder in Colorado. Boulder's location on the border between the Colorado Rockies and the Great Plains provides a diverse range of physical characteristics.

The Agricultural Core includes a large part of the interior plains, spreading from the Appalachians to the Rockies.

Some similarities in the terrain are obvious. Again, a common theme between this region and Colorado is agriculture. It's obvious by the name that the Agricultural Core region is extremely focused on agriculture... 

Wheat, hay, barley, and livestock are commonly produced in both Colorado and places such as Iowa, Illinois, Indiana, etc.

Sources:

The Regional Landscapes of the United States and Canada

http://geography.howstuffworks.com/united-states/geography-of-colorado2.htm