We've all heard that crime doesn't pay. Peace, it turns out, just might.

The newest edition of the U.S. Peace Index, developed by the Institute for Economics and Peace, ranks states by level of peacefulness. The index is based on five primary indicators: (1) number of homicides per 100,000 people, (2) number of violent crimes per 100,000 people, (3) number of people in jail per 100,000 people, (4) number of police ofﬁcers per 100,000 people and (5) general availability of small arms.

Combining these figures, the U.S. Peace Index calculates a number summarizing the overall peacefulness of each state, with low numbers being safer. Currently, the national average is 2.056.

Since 1995, the U.S. has become 8 percent safe, according to the index. Not all states have improved, though. New York's become 32.3 percent safer since 1991, but other states have actually become more dangerous, like North Dakota (47.7 percent more dangerous) and Tennessee (9.3 percent more dangerous). Generally, Southern states tended to be the least safe, with the region scoring 3.13 on the index, compared with the Northeast, calculated to be the safest region with a score of 1.99.

Reducing crime seems to have more benefits than just an increased sense of well-being, too, with the index's authors hinting that safety might have notable economic benefits. If the United States peace index was as low as Canada's (1.392 compared to 2.056), for example, the U.S. Peace Index's authors argue that state governments could save up to $89 billion in incarceration, medical, judicial and policing costs. Add to that an increase in nationwide productivity equivalent to a $272 billion stimulus, as well as 2.7 million newly-created jobs, and it starts to become pretty clear: peace pays.

Indicators are weighted, allowing homicides to carry the greatest significance, while availability of firearms carries the least. The index also groups into four categories an additional 37 secondary factors like high school graduation rate and median income: politics and demographics, education, health and economic conditions.

Below is the list of the 10 least peaceful states in the United States according to the Institute for Economics and Peace.

PHOTO GALLERY 10 Most Dangerous States