Regions in the United States contain multiple states with similar geographic characteristics. According to the Library of Congress Geographic Location Index, there are five ways to view regions of the United States.
In the Northeast/Northwest/Southwest regional map, the Southeastern states and Hawaii are unnamed regions. The Northeast region includes states East of the Mississippi River and North of the Ohio and Potomac rivers.
The Northwest region includes the part of United States between the western edge of Lake Superior and the Pacific Ocean. Southwestern states are west of the Mississippi River: Arkansas, Arizona, California, Colorado, Louisiana, Nevada, New Mexico, Oklahoma, Texas, Utah.
The United States can be described as having two major regions: East and West. The Eastern states are located east of the Mississippi River and the Western states are located west of the Mississippi River.
Northwest, Pacific states include those states that were once a part of Old Oregon country: Idaho, Oregon, Montana, Washington, Wyoming. The Southwestern states in this grouping are states that were once a part of the Spanish province of New Mexico: Arizona, California, Colorado, Nevada, New Mexico and Utah.
Southern states are located below the Mason-Dixon Line and Ohio River, from the western Texas border to the Atlantic Ocean. In this classification system, the Northeastern region and Hawaii remain unnamed.
The Atlantic region encompasses all states from Maine to Florida that border or nearly border the Atlantic Ocean.
Middle Western states span between the Rocky Mountains to the Allegheny Mountains, north of the Ohio River and southern border of Missouri and Kansas. States lying outside these two regions remain unnamed in this region classification system.
The largest classification of regions, this grouping includes Mid-Atlantic States, New England, Pacific States, the Rocky Mountain Region, South Atlantic States
Southwest, and Old (Southwestern U.S. before cessions of land from Mexico following Mexican War). New England is a commonly used region from this map classification that includes Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island and Vermont.
