State Similarity Index

Have you ever wondered how similar or different two states are? The State Similarity Index attempts to quantify how similar American states are to each other relative to other states. For example, one might intuitively know that West Virginia is more like Alabama than Alaska but less like West Virginia than Kentucky. The index is a statistically-based way to measure this. The index weights equally five major aspects of states: their demographics, culture, politics, infrastructure, and geography. The research combines more than 1,000 different data points. Each aspect was roughly balanced evenly between quantity/percentage and quality/type. The following paragraphs explain the exact criteria for the index more in depth:

Overall Rubric

Demographics

Individuals & their personal characteristics

Race: Whites, Latinos, Blacks, Asians, Pacific Islanders, Native Americans
Ancestry: National Origin

Religion: Religious Denominations
Age: Average Age, Children, Elderly
Marriage: Married, Divorced, Single

Appearance: Height, Weight, Gender
Income: Average Income, Poverty, Millionaires
Education: High School Graduates, College Graduates, Advanced Degrees

Culture

Society & its common activities

Religion: Belief and Religious Denomination
History: Native Americans, Colonization, Civil War, Segregation
Speech: Accents and Native Languages

Entertainment: Sports, Exercise, Music, Television
Violence: Guns, Hunting, Murder, Incarceration
Health: Tobacco, Alcohol, Drugs, Suicide

Behavior: Personality, Individualism, Charity, Tolerance
Organizations: Union Membership, Military Enlistment, College Conferences, University Standards

Politics

Government & its adopted policies

Legislative: Senators, Congressmen

Executive: Presidential Elections, Gubernatorial Elections, Primaries
Judicial: State Court, Court of Appeals, Judicial Selection, Sentencing
Vices: Smoking, Marijuana, Alcohol, Gambling

Sex: Consent, Incest, Abortion, Surrogacy
Budget: Taxation, Expenditures
Protections: Rights, Immigration, Minimum Wage, Unionization

Procedures: Gun Control, Voting Laws, Education Laws, Traffic Laws

Infrastructure

Technology & essential equipment

Energy: Use, Electrical Grid, Sources
Transportation: Mass Transit, Airplanes, Railways, Roadways

Water: Use, Content, Distribution
Construction: Homes, Skyscrapers, Age
Industry: Mining, Manufacturing

Logistics: Railroad Tonnage, Port Tonnage, Pipelines, Semi-Trucks
Communication: Radio, Telephone, Television, Internet
Emergency: Doctors, Firefighters, Police, Military

Geography

Environment & its physical features

Climate: Temperature, Precipitation
Land Cover: Forest, Farms, Pastures, Barren Lands
Vegetation Type: Crops, Habitats, Floristic Regions

Location: Time Zone, Latitude
Adjacency: Hydrologic Region, Geologic Region
Slope: Mountains, Elevation

Water: Freshwater, Coastal water
Anthropization: Population, Built-Up Area

A full distance matrix of all states was completed, revealing similarities and differences between individual US states.

The data from the Index was then used to generate an accurate Regions of the United States Map.

Notes

If a characteristic was nearly universal, then it was not included in the calculation. For example, only Louisiana is the only state with a judicial system that combines common law with civil law. Therefore this characteristic was not used since it would not make a difference for a vast majority of comparisons.
Similarly, if a characteristic is almost never shared between states, then it was not included in the calculation as well.

Some characteristics are difficult to quantify or hard to find statistics for. For example, architecture style would have been included into the index if there were relevant statistics readily available. However, since over 100 individual statistics were used, adding in more would not significantly change the overall score for a country. In addition, many statistics highly correlate with one another.
The index has been slightly revised since it was first created in response to feedback. This is version 3.0. Race, religion, history, language and climate have all been given a heavier weight than in the first iteration.