This is a list of some of the ways
regions is defined in the United States. Many regions are defined in law or regulations by the federal government; others by shared culture and history, and others by economic factors.
Census Bureau-designated regions and divisions
U.S. Census Bureau Regions and Divisions.
Since 1950, the United States Census Bureau defines four statistical regions, with nine divisions.
 The Census Bureau region definition is "widely used ... for data collection and analysis",  and is the most commonly used classification system.    
 Region 1:
Midwest (Before June 1984, the Midwest Region was designated as the North Central Region.)
 Division 3:
East North Central ( Illinois, Indiana, Michigan, Ohio, and Wisconsin) Division 4: West North Central ( Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota) Region 3:
Region 4: West
Mountain ( Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, and Wyoming) Division 9: Pacific ( Alaska, California, Hawaii, Oregon, and Washington)
Puerto Rico and other US territories are not part of any census region or census division.
Federal Reserve Banks
Federal Reserve districts.
Federal Reserve Act of 1913 divided the country into twelve districts with a central Federal Reserve Bank in each district. These twelve Federal Reserve Banks together form a major part of the Federal Reserve System, the central banking system of the United States. Missouri is the only U.S. state to have two Federal Reserve locations within its borders, but several other states are also divided between more than one district.
Dallas San Francisco
U.S. time zones. (Some U.S. time zones are not on this map.)
UTC−12:00 ( Baker Island, Howland Island)
Samoa Time Zone ( American Samoa, Jarvis Island, Kingman Reef, Midway Atoll, Palmyra Atoll)
Hawaii–Aleutian Time Zone ( Hawaii, Aleutian Islands (Alaska), Johnston Atoll)
Alaska Time Zone ( Alaska, excluding Aleutian Islands)
Pacific Time Zone
Arizona Time Zone (excluding the Navajo Nation) 
Mountain Time Zone (excluding most parts of Arizona)
Central Time Zone
Eastern Time Zone
Atlantic Time Zone ( Puerto Rico, U.S. Virgin Islands)
Chamorro Time Zone ( Guam, Northern Mariana Islands) Wake Island Time Zone ( Wake Island)
Courts of Appeals circuits
U.S. Courts of Appeals circuits
Federal Circuit is not a regional circuit. Its jurisdiction is nationwide but based on the subject matter.
Bureau of Economic Analysis regions
Bureau of Economic Analysis regions
Bureau of Economic Analysis defines regions for comparison of economic data.
 New England:
Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont Mideast:
Delaware, District of Columbia, Maryland, New Jersey, New York, and Pennsylvania Great Lakes:
Illinois, Indiana, Michigan, Ohio, and Wisconsin Plains:
Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, and South Dakota Southeast:
Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, Mississippi, North Carolina, South Carolina, Tennessee, Virginia, and West Virginia Southwest:
Arizona, New Mexico, Oklahoma, and Texas Rocky Mountain:
Colorado, Idaho, Montana, Utah, and Wyoming Far West: Alaska, California, Hawaii, Nevada, Oregon, and Washington
Intrastate and intraterritory regions
A map of Alabama regions.
Map highlighting the 9 official regions of Connecticut
Connecticut has 9 official planning regions. These regions operate as
councils of governments, and are recognized as county equivalents by the U.S. Census Bureau.
Some of Connecticut's informal regions include:
"Upstate" or "Up North"
District of Columbia
Local vernacular regions
Southern Illinois is also known as "Little Egypt".
A map of Louisiana's regions
Regions shared with other states:
Regions of New York as defined by the New York State Department of Economic Development.
Western New York
counties: Niagara, Erie, Chautauqua, Cattaraugus, Allegany
counties : Orleans, Genesee, Wyoming, Monroe, Livingston, Wayne, Ontario, Yates, Seneca
counties: Steuben, Schuyler, Chemung, Tompkins, Tioga, Chenango, Broome, Delaware
Central New York
counties: Cortland, Cayuga, Onondaga, Oswego, Madison
counties : St. Lawrence, Lewis, Jefferson, Hamilton, Essex, Clinton, Franklin
counties: Oneida, Herkimer, Fulton, Montgomery, Otsego, Schoharie
counties : Albany, Columbia, Greene, Warren, Washington, Saratoga, Schenectady, Rensselaer
counties: Sullivan, Ulster, Dutchess, Orange, Putnam, Rockland, Westchester
New York City
counties (boroughs): New York ( Manhattan), Bronx ( The Bronx), Queens ( Queens), Kings ( Brooklyn), Richmond ( Staten Island)
Regions of North Carolina.
Northern Mariana Islands
East River and West River
U.S. Minor Outlying Islands
U.S. Virgin Islands
Wisconsin's five geographic regions
Wisconsin can be divided into
five geographic regions.