Bible belt

A bible belt is an area of fundamentalist protestantism, where reliance on teachings from the holy books of Christianity is at its most pervasive, and often its most literal. In particular, the Bible Belt (with capitals) covers a number of southern and midwestern states of the U.S.

The "belt" terminology is common in the U.S. to describe regions with a roughly east-west orientation that share a feature: e.g., the Rust Belt (declining industrial areas) and the Sun Belt (hot-weather states in the south and west).