Of the 50 states in the U.S., those in the South continue to be the most religious, according to a recently released Gallup survey.

For the ninth year, Mississippi came in as the most religious state, with 59 percent its residents being "very religious." Alabama followed, with 56 percent of very religious residents.

Other southern states that came in the 10 most religious states include South Carolina (52 percent), Arkansas (52 percent), Louisiana (50 percent), Tennessee (50 percent), Oklahoma (49 percent) and Georgia (47 percent).

Only two states in the top 10 were not from the South: Utah (54 percent) and South Dakota (53 percent).

Vermont was found to be the least religious state, as 21 percent were "very religious." Maine (23 percent) and Massachusetts (25 percent) followed.

The survey classified residents as "very religious," "moderately religious," or "nonreligious" based on their survey responses on how important they believe religion is, and how often they attend church, Gallup explained.

"Very religious Americans say religion is important to them and report attending services every week or almost every week," the study states. "Nonreligious Americans are those for whom religion is not important and who seldom attend religious services. Moderately religious Americans meet just one of the criteria, saying either religion is important or that they attend services almost every week or more often."

Frank Newport, the editor-in-chief of Gallup, said that while there are no "clear-cut" explanations to the differing levels of religiosity state-by-state, much of it may have to do with a state's culture, "which in turn derives from many years of religious history."

"Children in highly religious states generally end up being more religious than children who grow up in less religious states," said Newport. "Persons moving to Mississippi may find themselves more likely to attend religious services because so many others are doing so, while persons moving to Vermont may be less inclined to attend because so few of their neighbors do."