From coast to coast, American whiskey producers are expanding their repertoires beyond the patriotic staple of bourbon and newly resurgent rye. The burgeoning, brave new world of whiskey that's now being explored is the domain of the American single malt. Just don't call it Scotch.

While bourbon and rye have histories stretching back hundreds of years in the United States, single malts weren't to be found. Quite simply, single malt whisky was equated exclusively with Scotch in the minds of most. A few American trailblazers emerged roughly two decades ago, and today, dozens more are finally following suit.

What Is an American Single Malt?

The straightforward definition of a single malt whiskey is one that is produced at a single distillery, using malted barley as the only grain in the mash bill. And while single malts are produced throughout the world, they're most commonly found in Scotland.

The U.S. Alcohol and Tobacco Tax and Trade Bureau (TTB), which regulates all legal categories and labeling requirements for alcohol in the country, doesn't currently offer a definition for an American single malt. Instead, it provides a more generic "malt whisky" classification. In the past, American single malt production has been so minuscule that there was never a need to slap a strict regulatory definition on it.

A single malt whiskey is produced at a single distillery, using malted barley as the only grain in the mash bill.

The vague category of malt whisky which the TTB does have could include single malts, but it also incorporates what is known in Scotland as grain whisky—whisky made from malted barley, as well as other grains, such as corn. Therefore, it's basically muddying the waters by clumping multiple styles together.

A defined American single malt category, though, could be as simple as: whiskey distilled from 100 percent malted barley by a single distillery within the United States. It's the American equivalent to single malt Scotch.

New Styles

As the craft distilling movement has taken hold, there are now dozens of distilleries producing American single malts, and a vast range of styles are beginning to emerge. (Consider how diverse the regional climate variation is in the United States—remember that weather and climate impact the way a whiskey ages.) In Texas and the southwest of the country, smoky single malts are beginning to appear. Meanwhile, along the coasts, producers are capturing the same salty profiles beloved in certain Scotches. How all of these different styles end up being classified and defined will play out in the years ahead.

Early efforts have already been made to classify American single malts. Most notably, several months ago, a prominent group of American distilleries known for making single malt whiskey held what has been dubbed "the American single malt summit." The goal was to figure out how to appropriately boost this emerging category, so that it's recognized and understood by consumers, gets appropriate shelf space at stores, and stands apart from both other American-made whiskeys and Scotch.

In the meantime, the best way to learn about the American single malt is to taste some of what the category has to offer. Here are a dozen distilleries worth exploring, representing not only some of the finest American single malt whiskey being made right now, but also the category's exciting diversity and utterly huge range of possibilities.

American Single Malt producers to know

1) Balcones Distilling (Waco, Texas): Now steered by head distiller Jared Himstedt, Balcones produces an array of whiskeys, including their Balcones "1" Texas Single Malt. One regional difference here is the need to combat that Texas heat and avoid over-aging the whiskey. The "1" Texas Single Malt is big and bold, with a mixture of rich malt and toffee, dried fruits, and dry, oaky spice.

2) Corsair Distillery (Nashville, Tennessee): Corsair's original distillery was located in Kentucky, and that space is now dedicated to their non-whiskey spirits. Nashville is where their whiskey gets made, and founder Darek Bell is known for his wildly inventive and experimental releases. Perhaps their most well-known whiskey is Triple Smoke, a single malt made with three types of smoked malted barley, using peat, along with cherrywood and beachwood. It tastes big and smoky, but with a rather fruity and sweet side from the cherrywood.

3) FEW Spirits (Evanston, Illinois): FEW is best known for their bourbon and rye, along with an exciting lineup of gins. FEW also makes a single malt, as well. According to founder Paul Hletko, they also use a portion of cherrywood-smoked malt, along with un-smoked malt. FEW Single Malt is spicy and malty, with a prominent wood influence.

4) Hamilton Distillers (Tucson, Arizona): Hamilton Distillers produces the Del Bac line of single malt whiskeys, spearheaded by their signature Del Bac Dorado, a mesquite-smoked single malt. Owner Stephen Paul makes use of a unique two part germination and kilning system, which allows fine control of the smoking process. Dorado is all big mesquite barbecue, with peppers and spice, plus a background sweetness.

5) Hillrock Estate Distillery (Ancram, New York): As an "estate" distillery, Hillrock handles the entire production process for their whiskeys, from growing the grain, to floor-malting the barley for their single malt. Hillrock is best known for its Solera Aged Bourbon, but it also make rye, and single malt. The single malt release is a dry, spicy whiskey, with oak, grain, vanilla, and leather.

6) House Spirits (Portland, Oregon): House Spirits has built up a following for their Aviation Gin, but they also produce other spirits, including Westward Oregon Straight Malt Whiskey. Co-owner and CEO Tom Mooney makes use of locally grown barley, and ages the whiskey in full-size barrels. Westward offers a cross of rich, malty sweetness, with a dry, spicy oak influence.

7) Ranger Creek (San Antonio, Texas): Ranger Creek Rimfire is a single malt smoked with Texas mesquite. Co-founder Mark McDavid cold smokes his barley using a rigged shipping container that serves as a smoker. Less intense on the mesquite front than the Del Bac, although still quite smoky, Rimfire also showcases spice, and a sweet side offering chocolate, molasses, and vanilla.

8) Sante Fe Spirits (Santa Fe, New Mexico): Santa Fe produces a diverse lineup of spirits, one of which is their Colkegan Single Malt Whiskey. They also utilize mesquite, with a mix of 30 percent smoked and 70 percent unsmoked barley. Colkegan is smoky, but not overpowering on the mesquite side, with a big but smooth profile. It also offers dry leather, oak and tobacco, along with hints ranging from vanilla to citrus.

9) St. George Spirits (Alameda, California): The St. George Single Malt Lot series is highly acclaimed, and when it debuted way back in 2000, it was one of the very first American single malts. A new release is offered annually, with 2015's Lot 15 being the most recent. The profile therefore changes from year to year, but expect a lighter, fruitier whisky overall, with floral and herbal notes. St. George also just released a new single malt expression, Baller Single Malt, intended to be drier and smokier.

10) Stranahan's (Denver, Colorado): Stranahan's Colorado Whiskey may not be advertised as a "single malt," but that's exactly what it is—and they're one of only a handful of American distilleries whose sole focus is on single malt whiskey. Stranahan's also calls their whiskey Rocky Mountain Whiskey, and it's made with Rocky Mountain water and locally grown barley. The whiskey offers a grain and oak profile, with sweeter notes of toffee and vanilla, along with spice and leather.

11) Tuthilltown Spirits Distillery (Gardiner, New York): Tuthilltown produces the Hudson Whiskey lineup, along with a number of other spirits. Their Hudson Baby Bourbon may be the most well known of the bunch, but there's a Hudson Single Malt, too. Aged in small barrels, the whiskey showcases a hefty dose of dry oak and char, along with barley and grain, vanilla, and spice.

12) Westland Distillery (Seattle, Washington): If there's a single distillery most prominently carrying the flag of the American single malt, it's Westland. They offer a range of Westland American Single Malt Whiskeys, including their flagship American Oak, along with Peated and Sherry Wood expressions. Master distiller Matt Hofmann is not only all about single malt, he's also all about the distillery's Pacific Northwest presence. Westland uses locally grown barley, and distills well as barrels made from the region's forests, and now even locally grown peat, too. The American Oak offers subtle roasted coffee and creamy chocolate notes, along with bits of oak, smoke and fruit.

Editor: Kat Odell

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