Bourbon, Tennessee Whiskey, and the Rules That Separate Them
Every bourbon is a whiskey. Not every whiskey is a bourbon. And Tennessee whiskey adds one more step.
By TMOWSA · 2026-09-20 · Reviewed 2026-09-20
Whiskey
Whiskey is a spirit distilled from fermented grain and, in most categories, aged in oak. That is the whole of the family.
Bourbon
Under United States federal standards of identity, bourbon must be:
- made in the United States
- made from a grain mixture of at least 51% corn
- distilled to no more than 160 proof
- put into the barrel at no more than 125 proof
- aged in new charred oak containers
- bottled at no less than 80 proof
- free of added colouring, flavouring or other additives
Nothing in those rules mentions Kentucky. Bourbon can legally be made in any state.
"Straight bourbon" adds a minimum of two years in the barrel. If a straight bourbon is aged less than four years, the label must state the age.
Sour mash
Sour mash is a process, not a category. A portion of the spent, acidic mash from a previous distillation is added to the next batch. The acidity steadies the pH, which keeps unwanted bacteria down and makes fermentation more consistent from batch to batch. It is common practice across the category rather than a mark of distinction.
Tennessee whiskey
Tennessee state law defines Tennessee whiskey as a whiskey that meets the bourbon requirements, is made in Tennessee, and is filtered through maple charcoal before barrelling. That filtering step is known as the Lincoln County Process. The statute carves out an exception for a distiller operating in Lincoln County as of a set date.
So the short version: Tennessee whiskey is bourbon-plus-charcoal-plus-place.
We need each other.
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