Too often when a bartender is asked which bourbons his or her bar carries, the list invariably includes Jack Daniel’s sour-mash Tennessee whiskey. But as most residents of the Volunteer State know, Tennessee whiskey is an entirely different libation from bourbon, even though they share many traits. Bourbon must be made in the United States, but contrary to popular belief, it can be made anywhere in the country. It is by a unique combination of history and geography that 95 percent of all bourbon is now made in…