Mississippi holds onto its title as most religious U.S. state, with 58 percent of its residents saying they are very religious, according to a Gallup poll released Wednesday (Feb. 13).

The least religious state? Vermont.

About 40 percent of Americans said they were "very religious," meaning religion is an important part of their daily life and that they attend religious services every week or nearly every week. Some 31 percent indicated they were nonreligious, or that religion wasn't an important part of their daily life and they seldom or never attend such services.

The 10 most and least religious states remained relatively constant from the 2011 numbers, with the only change being the inclusion of Hawaii in the least religious list in place of New York. [See full list of U.S. states and religiosity]

As expected, the South dominated the "most religious" list, while the 12 least religious states were located in New England. For instance, while just 14 percent of Alabama residents indicated they were nonreligious, 50 percent of those in New Hampshire said the same. (In addition to very religious and nonreligious, Gallup also had a "moderately religious" category.) Utah, which has a large Mormon population, and Oklahoma, which straddles the border between the South and the Midwest, were the only exceptions to the dominantly Southern states in the top 10 list.

Top 10 most religious states

Mississippi: 58 percent are very religious

Utah: 56 percent

Alabama: 56 percent

Louisiana: 53 percent

Arkansas: 52 percent

South Carolina: 52 percent

Tennessee: 50 percent

North Carolina: 50 percent

Georgia: 48 percent

Oklahoma: 48 percent

Bottom 10 (least religious states)

Vermont: 19 percent are very religious

New Hampshire: 23 percent

Maine: 24 percent

Massachusetts: 27 percent

Oregon: 29 percent

Rhode Island: 29 percent

District of Columbia: 30 percent

Washington (tie): 31 percent

Connecticut (tie): 31 percent

Alaska (tie): 31 percent

Hawaii (tie): 31 percent

Nevada (tie): 31 percent

The differences in religiosity across the United States may not be the result of underlying demographics (race or ethnicity) or religious identities (Catholic or Protestant majorities, for instance), but rather part of a state-level cultural phenomenon.

Story continues

Something about the state's culture, based partly on that state's history, may be behind residents' religiosity, Gallup suggests. "In other words, it can be hypothesized that a person moving to Mississippi is more likely to become personally more religious than if that same person moved to Vermont," Gallup officials write in a statement.

While overall seven in 10 Americans said they were either moderately or very religious, other Gallup poll results reported in January have shown a rise in "no religious identification" over time.

"Americans' expression of an explicit religious identity in response to a survey interviewer's question is one of many measures of religiosity, although by no means a definitive measure of a person's religiousness or spirituality," Gallup states. "The rise in 'nones' partly reflects changes in the general pattern of expression of religion in American society today — particularly including trends towards more 'unbranded,' casual, informal religion."

The just-released state-religion results are based on more than 348,000 interviews with adults ages 18 and older conducted from Jan. 1 to Dec. 31, 2012, as part of Gallup Daily tracking. The results were weighted to be representative of each state's adult population by gender, age, race, Hispanic ethnicity and education, based on Census data.

Follow LiveScience on Twitter @livescience. We're also on Facebook & Google+.

Copyright 2013 LiveScience, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.