Multiple options then, if not basing it off of the Great Northern Aggression
:
Regional divisions used by the United States Census Bureau
Region 1 (Northeast)
-Division 1 (New England)
--Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut
-Division 2 (Mid-Atlantic)
--New York, Pennsylvania, New Jersey
Region 2 (Midwest)
-Division 3 (East North Central)
--Wisconsin, Michigan, Illinois, Indiana, Ohio
-Division 4 (West North Central)
--North Dakota, South Dakota, Nebraska, Kansas, Minnesota, Iowa, Missouri
Region 3 (South)
-Division 5 (South Atlantic)
--Delaware, Maryland, District of Columbia, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Florida
-Division 6 (East South Central)
--Kentucky, Tennessee, Mississippi, Alabama
-Division 7 (West South Central)
--Oklahoma, Texas, Arkansas, Louisiana
Region 4 (West)
-Division 8 (Mountain)
--Idaho, Montana, Wyoming, Nevada, Utah, Colorado, Arizona, New Mexico
-Division 9 (Pacific)
--Alaska, Washington, Oregon, California, Hawaii