Regions of the United StatesI'm frequently asked about which region a state lies within, for instance, "Is Kansas a Midwestern state or a Central state?" Unfortunately, the U.S.A. is composed of many "regions" and there is no official designation for each state. You can place Kansas as a Midwestern state and just as easily call it a Central state, just as you could call Oregon a Pacific state and a Northwestern state (although the term Pacific Northwest is frequently also used.)
Below is a map that provides an indication of the diversity of regional terms used in the United States. This map provides just a small sample of the terms used. There are no boundaries on this map because these regions are of course relative and represent different things to different people.
Also see this listing of regions and their respective states here on my site.
Map copyright 2000 Matt Rosenberg and About.com