Cambridge is part of the most peaceful area in the country, according to the Institute for Economics & Peace’s United States Peace Index for the year and a USA Today story being touted by the the city’s public information office, Ini Tomeu.

Cambridge-Newton-Framingham is the most peaceful metropolitan area, while Maine finished first as the “most peaceful” state, Tomeu said Wednesday. The country is overall more peaceful than at any time in the past two decades, according to an April 24 article in the newspaper’s On Deadline blog.

The survey defines peace as the “absence of violence,” and the five criteria used in the ranking are the number of homicides per 100,000 people; number of violent crimes; incarceration rate; number of police employees; and availability of small arms, Tomeu said. Indeed, Cambridge police said in February that the city was seeing its lowest crime rate since 1963.

The survey, first issued in 1991, finds that the United States improved in all five categories over 2011, including a 3.2 percent drop in homicides and a 5.5 percent dip in violent crimes. The survey finds, however, that the decrease in officially recorded violence has been partially offset by increases in violence in prison.

The survey, once again, notes a strong correlation between peace and economic opportunity, health, education and social capital.

The runner-up for Cambridge-Newton-Framingham is Edison-New Brunswick, N.J., then Seattle-Bellevue-Everett, Wash., in third place. Massachusetts appears on the list again at No. 6, sharing with Rhode Island in the Providence-New Bedford-Fall River area.

This month already saw Cambridge called the most walkable city in the country and the best city in New England.

This post took significant amounts of information from a press release.