The Bible Belt is a region of the Southern United States in which socially conservative Protestant Christianity plays a strong role in society. Church attendance across the denominations is generally higher than the nation's average. The region contrasts with the religiously diverse Midwest and Great Lakes, and the Mormon corridor in Utah and southern Idaho.

Whereas the states with the highest percentage of residents identifying as non-religious are in the West and New England regions of the United States (with Vermont at 37%, ranking the highest), in the Bible Belt state of Alabama it is just 12%, and Tennessee has the highest proportion of evangelical Protestants, at 52%. The evangelical influence is strongest in northern Georgia, Tennessee, Alabama, Mississippi, North Carolina, southern and western Virginia, West Virginia, the Upstate region of South Carolina, and East Texas.

The earliest known usage of the term "Bible Belt" was by American journalist and social commentator H. L. Mencken, who in 1924 wrote in the Chicago Daily Tribune: "The old game, I suspect, is beginning to play out in the Bible Belt." In 1927, Mencken claimed the term as his invention. The term is now also used in other countries for regions with higher religious doctrine adoption.