The name "Bible Belt" has been applied historically to the South and parts of the Midwest, but is more commonly identified with the South. In a 1961 study, Wilbur Zelinsky delineated the region as the area in which Protestant denominations, especially Southern Baptist, Methodist, and evangelical, are the predominant religious affiliation. The region thus defined included most of the Southern United States, including most of Texas and Oklahoma, and in the states south of the Ohio River, and extending east to include central West Virginia and Virginia, from the Shenandoah Valley southward. In addition, the Bible Belt covers most of Missouri and Kentucky and southern parts of Illinois, Indiana, and Ohio. On the other hand, areas in the South which are not considered part of the Bible Belt include heavily Catholic Southern Louisiana, central and southern Florida, which have been settled mainly by immigrants and Americans from elsewhere in the country, and overwhelmingly Hispanic South Texas. A 1978 study by Charles Heatwole identified the Bible Belt as the region dominated by 24 fundamentalist Protestant denominations, corresponding to essentially the same area mapped by Zelinsky.
According to Stephen W. Tweedie, an Associate Professor Emeritus in the Department of Geography at Oklahoma State University, the Bible Belt is now viewed in terms of numerical concentration of the audience for religious television. He finds two belts: one more eastern that stretches from Florida, (excluding Miami, Tampa and South Florida), through Alabama, Tennessee, Kentucky, Georgia, North and South Carolina, and into Southern Virginia ; and another concentrated in Texas (excluding El Paso, and South Texas), Arkansas, Louisiana, (excluding New Orleans and Acadiana), Oklahoma, Missouri (excluding St. Louis), Kansas, and Mississippi. "[H]is research also broke the Bible Belt into two core regions, a western region and an eastern region. Tweedie's western Bible Belt was focused on a core that extended from Little Rock, Arkansas to Tulsa, Oklahoma. His eastern Bible Belt was focused on a core that included the major population centers of Virginia and North Carolina.
A study was commissioned by the American Bible Society to survey the importance of the Bible in the metropolitan areas of the United States. The report was based on 42,855 interviews conducted between 2005 and 2012. It determined the 10 most "Bible-minded" cities were Knoxville, Tennessee; Shreveport, Louisiana; Chattanooga, Tennessee; Birmingham, Alabama; Jackson, Mississippi; Springfield, Missouri; Charlotte, North Carolina;, Lynchburg, Virginia; Huntsville-Decatur, Alabama; and Charleston, West Virginia.
In addition to the South, there is a smaller Bible Belt in West Michigan, centered around the heavily Dutch-influenced cities of Holland and Grand Rapids. Christian colleges in that region include Calvin College, Hope College, Cornerstone University, Grace Bible College, and Kuyper College. West Michigan is generally fiscally and socially conservative.