"Bourbon as a category is on fire," said Bill Thomas, a Washington, D.C., bar owner whose establishments include Jack Rose Dining Saloon. "Every week, there's stuff that's out of stock."
Expansions have occurred at Jim Beam, Evan Williams, Wild Turkey, Maker's Mark, Buffalo Trace and Woodford Reserve. Global liquor giant Diageo PLC recently announced plans to build a new distillery in Kentucky. Microdistilleries are getting a foothold in the state.
Every drop of bourbon is precious for producers trying to keep up with demand.
"If they had more, they could sell it right now," said Fred Noe, Jim Beam's master distiller and descendant of Jacob Beam, who set up his first Kentucky still in 1795.
The disparity between supply and demand has put extra pressure on the distilleries.
In early 2013, Maker's Mark caused a backlash when it announced it was cutting the amount of alcohol in each bottle to stretch its whiskey supplies. The brand known for its red wax seal quickly scrapped the idea.
In the U.S., total revenues for bourbon and Tennessee whiskey reached $2.4 billion last year, a 10.2 percent increase, according to the Distilled Spirits Council. Volume was up nearly 7 percent to 18 million cases, it said.
The two spirits claimed 34 percent of the U.S. whiskey market in 2013, putting it ahead of the Canadian, Scotch, blended and Irish whiskey categories.
The industry lumps bourbon and Tennessee whiskey into one category. Both are produced in the same way with similar ingredients, but Tennessee whiskeys are charcoal mellowed before going into the barrel to age, while bourbon isn't.
Exports of bourbon and Tennessee whiskey surpassed $1 billion for the first time ever in 2013, the council said.
"It's never been like this in my lifetime," said Bill Samuels Jr., who retired after a long career as the top executive at Maker's Mark, the brand started by his parents. "It doesn't feel like a fad. It feels like a legitimate trend."