Rye is the spice of life for American whiskey.

Also known as Secale cereale L., the erect annual grass towers over others with its flat leaf blades, dense flower spikes, and long awns. The hardy grain endures drought, harsh winters, sandy soils, and low fertility to grow just about wherever planted. Farmers use it as a cover crop to suck up unwanted nutrients and attract pests from weaker plants. If the Zombie apocalypse or a nuclear war breaks out, good old steady rye would survive over soybeans, sugar beets, and corn—well, maybe not the GMO corn, that’s genetically modified.

To us whiskey drinkers, modern rye offers up descendants of yesterday’s Pennsylvania rye distilleries that cranked out rye whiskey once commonly referred to as Monongahela, named after the distillery’s water source—the Monongahela River. Pioneers traveled west with jugs and barrels of Monongahela to barter, trade, and drink. “The best and greatest quantity of rye whiskey is made on this {Monongahela} river,” wrote traveler Zadok Craker in the 1817 book, The Navigator.

Rye is the welcomed secondary grain in bourbon’s 51 percent corn minimum mash bill. And rye is the undisputed spiced-up backbone of rye whiskey.

Perhaps, no grain stands out stronger or more pronounced in a dram than rye. Its spicy flavor profile is undeniable.

For the past decade, rye whiskeys have jumped out from obscurity and stolen America’s cocktail heart.

That’s largely because rye whiskey was available for purchase. Most of the new juice was coming from former Seagram’s distillery in Lawrenceburg, Ind., which under new management (Lawrenceburg Distillers Indiana and now MGP Ingredients) sold bulk rye whiskey stocks to the likes of Redemption Rye and Bulleit Rye.

As Indiana rye whiskey infiltrated the market, Jim Beam, Rittenhouse, and other rye whiskeys reclaimed their popularity. Suddenly, the rye whiskey that was only being distilled once a season was competing with bourbon at Jim Beam and Heaven Hill Distilleries for still time.

All the while, you and I chased higher-rye bourbons, such as Four Roses, giving the crop its greatest demand since 1922, when Americans picked more than 6.7 million acres of rye.

From an agricultural planting perspective, though, rye is a forgotten crop, relegated to cover cropping for corn and soybeans, enjoying bug bites and keeping the weeds away from the cash crops. Since rye is so resilient, farmers basically use it to block the moneymakers from all the bad stuff.

“Rye is a minor crop, often planted but not harvested for grain,” says Ed Allen, the cross commodity analyst for the U.S. Department of Agriculture.  

Patrick Westhoff, the director of the Food and Agricultural Policy Research Institute at the University of Missouri-Columbia, says rye is in the same boat as other crops—they’re all having “a hard time competing with corn. We definitely have increased overall acreage of corn in this country,” he says. “There’s less land available for pretty much everything else you are going to have. High corn prices, good corn returns, definitely has pushed people to plant as many acres of corn they can.”

So, where are bourbon and rye whiskey distillers getting their rye? Canada and Europe.

Alas, only a handful of American distillers actually use U.S.-grown rye. Buffalo Trace Distillery says it buys some rye from North Dakota, but most larger distilleries are forced to purchase rye elsewhere.

If you’re like me, when I first learned this, you’re scratching your head. Canada and Europe, not the good old U S of A, grow rye for American whiskeys? Fortunately, the federal government does not mandate U.S.-grown grains for American whiskey making.

And this may not be a bad thing. Former Four Roses master distiller and consultant Jim Rutledge believes European rye is better for whiskey making anyway.

“Rye is very difficult to ferment,” Rutledge says. “The best rye for distillation (flavor-wise) is grown in colder climates.”

Rutledge says he’s mostly looking at rye from Canada and European countries, looking for a flavor profile and “falling numbers,” a measure of enzyme activities.

“Rye is very high ratio of enzymes – much higher than other grains – and the higher the enzyme level the more foaming during the fermentation process. If the enzymes are too high the foaming during fermentation is almost uncontrollable,” Rutledge says. “I’ve seen fermenters filled only half full and foam over when enzymes are too high. So, the selection process is a combination of desired sensory perception, starch content, and enzyme level and the best rye in the last 15 to 18 years has been found in northern European countries.”

The EU represents roughly 53 percent of the world’s rye plantings, while Canada is easily North America’s rye leader. And U.S. farmers are not going to stop planting corn anytime soon. The money is just too good, and rye doesn’t pay.

So, the next bourbon you have with a rye mash bill, just know you’re not drinking an American-based rye.

Those days are long gone.