Nine of the 10 most religious states are clustered in the South, while the least religious ones are in New England and the West, according to new Gallup data.

The data, mapped above, show that more than four in 10 Americans are “very religious,” which is defined as those for whom religion is an important part of their daily lives and who attend services most weeks. For roughly three in 10, only one or the other apply, while for another three in 10 neither do. The rates have been relatively unchanged since Gallup began collecting the data in 2008.

The wide variation by state could be caused by several factors, according to the polling organization. For one, followers of certain religions such as Protestants just tend to be more religious. But geography plays a big role, too. In fact, region is closely associated with religiousness, Gallup notes:

[P]revious research shows that even among those in the different regions who have the same religious identity, state-level cultural differences still affect average religiousness. Protestants in Mississippi are more religious than Protestants in Vermont, and those with no religious identity in Mississippi are more religious than those with no religious identity in Vermont.

Additionally, although states vary significantly in their racial and ethnic composition, differences in religiousness between states persist even among residents of the same races. Whites in Mississippi are more religious than whites in Vermont, and blacks in New England are less religious than blacks in the South.

Catholics dominate the least religious states; Southern Baptists dominate the most

Last December, we looked at a series of maps that showed how religion breaks down in the nation’s states and counties and the first offers another layer through which to view Gallup’s regional breakdown. In Southern counties, where religiousness is strongest, the Southern Baptist Convention is almost universally the most popular religion. Counties in the Northeast and Western states, where the smallest share of people are very religious, are largely dominated by the Catholic Church.

Many weakly religious states also have high religious diversity

Religious diversity, to a lesser degree, also shows similar regional variation. The states in the Northeast and West where religious affiliation is weakest also have high religious diversity. While the areas in the South and Utah, where religiousness is highest, have less religious diversity.