
The State Similarity Index attempts to quantify how similar American states are to each other relative to other states. The index is a statistically-based way to measure this. It weighs equally five major aspects of states: their demographics, culture, politics, infrastructure, and geography. The methodology is exactly the same for each state.

The data from the State Similarity Index was used to cluster American states into different regions. Some unique states, like Alaska and Hawaii, are very difficult to group with other states. Therefore, it was necessary to make the largest regions still have a great deal of variation within them. This resulted in 6 distinct macro-regions:
- Alaska
- Northeast
- West
- South
- Midwest
- Hawaii
Please see this article, which compares these groupings to other regional maps created by geographers. These macro-regions are further broken up into sub-regions, since there are still some significant differences within them. States as different as California and Utah are still grouped together. Please note that simply using the hierarchical clustering does not tell the full story, since some states can have nearly equal attributes of two different regions. This is especially true from Missouri and Pennsylvania. Further analysis of the data requires comparing each state’s average to the resulting regions and creating a map of linkages between similar states to create a more refined map.
The states in each region and their individual pages are as follows:
Alaska
Alaska
Northeast
North New England
— Maine, New Hampshire, Vermont
BosWash
— Connecticut, Massachusetts, New Jersey, New York, Rhode Island
— Delaware, Maryland
West
Rocky Mountain
— Idaho, Montana, Wyoming
— Colorado
— Utah
Pacific Coast
— Oregon, Washington
— California
Southwest
— Arizona, Nevada
— New Mexico
South
Florida
— Florida
Texas
— Texas
Southeast
— Alabama, Arkansas, Kentucky, Louisiana, Missouri, Mississippi, Tennessee
— Georgia, North Carolina, South Carolina, Virginia
— Oklahoma
— West Virginia
Midwest
Great Lakes
— Illinois, Indiana, Michigan, Minnesota, Ohio, Pennsylvania, Wisconsin
Great Plains
— Iowa, Kansas, Nebraska, North Dakota, South Dakota
Hawaii
Hawaii
Here is the hierarchical clustering dendrogram, used to create the map:
Here is the resulting map:
Do you agree with these regions of the United States?
Please leave any thoughts in the comments section.