A dozen or so years ago, I was bumping down an overgrown logging road deep in the woods of northern Maine when I came upon a campsite in a clearing. It was all nice and tidy, save for three pieces of litter in the campfire ring: an empty carton of half-and-half, an empty handle of Popov Vodka, and an empty handle of Allen’s Coffee Flavored Brandy.

Suddenly, I was Kurtz heading upstream into Maine’s heart of coffee darkness.

Maine is state of considerable anomalies—coves covered by bowling-ball-sized rocks locals refer to as “beaches;” the belief that temperatures in the 80s constitutes a heat wave; the verbose volcano of horror that is Stephen King—but the state’s most persistent aberration may be its lasting fondness for Allen’s Coffee Brandy.

The dominance of Allen’s since the 1970s is what Portland bar owner Andrew Volk calls a “Maine cultural oddity”—which may be an understatement, given that no other region is so dominated by a single outlier drink. Yes, there’s the pungently bitter Malört in Chicago, the bitterly sweet Fernet-Branca in San Francisco, and Korbel brandy in Wisconsin. But none of these beverages cast quite the shadow over a local market as Allen’s Coffee Brandy, which is to all other spirits in Maine what Gulliver is to the Lilliputians.

Consider: the single best-selling bottle of liquor in the state is the 1.75-liter handle of Allen’s Coffee Brandy, both in terms of volume and value. Last year, the state sold $5 million dollars of Allen’s handles to retailers—outpacing all other brands and bottle sizes. (Maine is one of 18 so-called control states, so a single state-sanctioned distributor sells to all retailers.) No other vodka, whiskey or rum came close. If you combine the sales in Maine of all the bottle sizes in which Allen’s is sold, the figure topped $10 million last year. (This was more than sales of all Jack Daniel’s, Jim Beam and Evan Williams, combined ; Kahlúa, a popular Mexican coffee liqueur and the sixth best-selling liqueur in the United States, sold just $1.7 million worth in Maine last year.)

Allen’s seems to be especially enjoyed by outdoorsmen. Volk, in Northern Hospitality, his forthcoming book about Maine cocktails co-authored with his wife and business partner, Briana, notes that the melting of the snow in late winter heralds a Maine phenomenon: “Empty bottles [of Allen’s] found in the spring along snowmobile trails are called ‘Lilies of the Tundra.’”

The campsite tableau I stumbled across was an aberration. I found the remnants of a Maine White Russian, which would be considered somewhat raised-pinky in the state—the more common variant is simply Allen’s and milk, mixed in any proportion you’d like, to make a rustic Sombrero. This concoction is common enough that it’s spawned numerous additional local names, including the Jackman Martini, Gorilla Milk, and Fat Ass in a Glass. Murray Carpenter in his book Caffeinated notes one other: “Burnt Trailer,” evidently named for the chaos that immediately follows overconsumption.

Allen’s Coffee Brandy is a product of M.S. Walker, based in Boston, Mass. The company began as a small pharmaceutical firm in the 1920s, and expanded into distribution of spirits shortly after the repeal of Prohibition in the early 1930s. Over time, M.S. Walker began producing its own liqueurs, with one line named after Leo Allen, the founder’s son-in-law, who had legendary marketing skills.

Allen’s coffee liqueur appeared in the 1960s. The company says the exact process is proprietary, but allows that it uses sourced coffee extract made via dual processes (percolation and distillation), and is mixed with a brandy base (not neutral grain spirits as is often reported), with a bit of vanilla and sugar to round it out.

By 1968, advertisements touted “Allen’s New Coffee Flavored Brandy joins Allen’s Famous Blackberry Flavored Brandy—now you can enjoy two great tastes.” It was thus perfectly positioned for explosive growth in the early 1970s, when Kahlúa, which had been around for four decades, was suddenly everywhere, often mixed up in Sombreros. (Historical footnote: Allen’s sought to capitalize on the Sombrero fad in the mid-1970s by selling bottled Coffee Sombreros and Banana Sombreros—the latter made with “Banana flavored brandy” and milk. These did not catch on.)

Why did Allen’s take root so firmly in Maine? No one quite knows. M.S. Walker claims that it was popular with lobstermen, who’d add a slug to their Thermos of morning coffee for additional warmth on their icy pre-dawn slogs out to sea. This makes sense, although the company admits there’s no evidence beyond anecdotes.

There was also the potency—Allen’s was originally bottled at 70-proof. It’s been lowered to 60-proof, but that still offers more punch per penny than Kahlúa’s 40-proof. And it was, and is, inexpensive—today, it’s around $15 for a handle—which doesn’t go unnoticed in a state that ranks in the bottom half of per-capita income nationally, and has a notably poor rural population.

What’s more, Volk suggests that coffee and milk may be part of New England’s cultural DNA. “Coffee milk”—a sort of chocolate milk precursor made with coffee extract—was a thing in the late 19 th century, apparently introduced by Italian immigrants in Providence, Rhode Island. Slimo Packing Company in New Bedford started producing a coffee syrup in the 1930s; in the 1940s Autocrat syrup rose in popularity and remains available today. Volk also notes that New England is home of Dunkin’ Donuts, which has trained generations to associate coffee with the soft taste of cream.

Volk insists that Allen’s should be more than a punch line, and is actually a fine product at a great price. He’s fond of the “bitter, near metallic, backbone along with a strong and sweet coffee flavor” and features it at his two bars—Portland Hunt + Alpine and Little Giant. Allen’s is notably front and center in his popular Espresso Martini variant, mixed with Plantation Rum and a locally brewed coffee extract. He says that serving up Allen’s offers a talking point with visitors—many guests come in who have never heard of it, and it offers a story waiting to unspool.

While handles of Allen’s Coffee Brandy remain the Gulliver of Maine, the Lilliputians are probing for weaknesses. The second best-selling product in Maine? Fireball, which sold more than 5 million 50-milliliter minis last year, the equivalent 43,030 nine-liter cases. Looking at all bottle sizes, Allen’s still holds a comfortable sales margin, moving 88,473 case equivalents of coffee brandy, compared to 66,087 of Fireball.

As it turns out, Fireball is actually made in Maine—at a Lewiston facility that the Sazerac Co. acquired a few years ago. Allen’s Coffee Brandy is made in Massachusetts, the state to the south that many Maine residents consider loathsome. Offering a potential future challenge, Sazerac Co. has stepped up its production of Mr. Boston Coffee Flavored Brandy, using coffee extract made in nearby Portland and touting “Made in Maine” on the label. (Sales of Mr. Boston coffee brandy to date remain less than one-tenth of Allen’s.)

Will Allen’s remain the dominant spirit in Maine, preserving one of the most idiosyncratic liquor dynasties in the nation? The answer may come down to convenience, and the ongoing battle between minis and handles. Allen’s isn’t widely available in nips. (“Historically this hasn’t been a strong consumer size for the brand,” says Gary Shaw, M.S. Walker’s vice president of sales. “We are not a shooter product.”) But one-shot portions have been booming in Maine—between fiscal years 2016 and 2017 the number of nips sold soared from 8.4 to an estimated 12 million, largely driven by sales of Fireball.

On the other hand, taste may prevail: Millennials love coffee, and the bean seems to be embraced in a wider array of products. And, historically, Mainers are reluctant to move from tradition.

Yet Allen’s being knocked from its throne would be momentous—like London losing Big Ben, Seattle the Space Needle or Rio the Christ the Redeemer. Allen’s Coffee Brandy is a landmark on the Maine spirituous-cultural landscape.

“It’s a mix of marketing and hazy memories,” Volk says. Which could be said for all great drinks.