AT Cask, a San Francisco liquor store run by the people who own that city’s high-end cocktail bars Rickhouse and Bourbon & Branch, the spirit most coveted by customers is George T. Stagg, a limited-production bourbon that can exceed 70 percent alcohol. The store’s owner, Brian Sheehy, said the waiting list for Stagg is 190 names long.

When Buffalo Trace distillery in Kentucky began rolling out Stagg a decade ago, the bourbon’s overpowering kick made it something of an anomaly. But today, Stagg isn’t going stag on the shelves. High-alcohol spirits — variously sailing under the terms overproof, cask-strength and barrel-strength — are becoming commonplace.

Scotches and bourbons dominate this bruising category. But recently, Redbreast, an esteemed Irish whiskey, released a cask-strength version. So-called “navy strength” gins have arrived, like Leopold Bros. of Colorado and Perry’s Tot from Brooklyn. And last year, DeLeón unveiled what it calls the first cask-strength tequila.

In general, alcohol levels have been creeping northward for a few years, as distillers aim to please bartenders and enthusiasts who thirst for a more potent dram — 50 percent has become the new 40 percent. But a goodly number of bottles are now speeding past even that mark, weighing in at anything from 51 to 70 percent, and beyond.