[Disclaimer-Any effort to define the geographic and cultural regions of the Continental United States based on state boundaries is contrived. If you don't like my definitions, get your own site, thanks.]
Ploughboy's Seven Regions of the Continental United States.
The Continental United States can be coarsely divided into seven geographical regions. Each region contains border states which serve as cultural and geographic transitional zones such as Missouri which contains elements of the American South or Kansas which is as much a part of the Great Plains as it is the Midwest.
New England Mid Atlantic South Midwest Great Plains Southwest Pacific Northwest