Saint Bethlehem or St. Bethlehem, also called "St. B" by locals, was an unincorporated community in Montgomery County, Tennessee, located just northeast of downtown Clarksville. St. Bethlehem has been incorporated into Clarksville city limits and is no longer a separate community, although locals still refer to that portion of Clarksville as "St. B". The main U.S. post office for Clarksville is in the St. Bethlehem community on U.S. Route 79.