The first-ever ranking of peace in the USA finds the nation overall is the most peaceful since 1995. Maine was ranked as the most peaceful state and Louisiana the least.

The rankings are drawn up by the Institute for Economics and Peace, an international think-tank that also issues a yearly Global Peace Index.

The index, which defines peace as "the absence of violence," looks at a set of five indicators, including homicide rates, violent crimes, percentage of the population in jail, number of police officers and availability of small arms (per 100,000 people) to rank the states. The data are drawn from the Bureau of Justice Statistics, FBI and Centers for Disease Control and Prevention.

On that basis, the institute finds that peace in the USA improved by 8% from 1995 to 2009.

It notes a significant correlation between a state's level of peace and its economic opportunity, education and health but finds peacefulness is politically neutral -- neither Republican nor Democratic states have an advantage.

Maine was ranked first overall because it topped the list of states on three of the five USPI indicators: number of violent crimes, number of police officers and incarceration rate.

Full rankings here.

The most peaceful states: 1. Maine; 2. New Hampshire; 3. Vermont; 4. Minnesota; 5. North Dakota; 6. Utah; 7. Massachusetts; 8.Rhode Island; 9. Iowa; 10. Washington.

The least peaceful states: 1. Louisiana; 2. Tennessee; 3. Nevada; 4. Florida; 5. Alabama; 6. Texas; 7. Arkansas; 8. Oklahoma; 9. South Carolina; 10. Maryland.