In the U.S. a region in the Southern or southeastern part of the country where Southern Baptist Convention denomination is strong, noted for conservative and evangelical values.
Bible + belt in the sense of a strip of area on a map.
The name is derived from the heavy emphasis on literal interpretations of the Bible in Evangelical denominations. The term "Bible Belt" was coined by the American journalist and social commentator, H.L. Mencken, in the early 1920s.
English Wiktionary. Available under CC-BY-SA license.