The classic "old fashioned" is the simplest of cocktails—sugar, bitters, and whiskey, stirred over ice, then served on the rocks with a citrus rind—and also, possibly, the best.

Thanks to the federal government, we almost lost it forever.

Different bartenders may take slightly varying approaches to the drink, but when executed well, the effect is the same: The recipe turns merely tolerable whiskey into something nuanced and delicious, adding complexity and character while smoothing over harsh edges. With good whiskey, it's a showcase for subtleties and strengths, taking a quality foundation and transforming it into something truly sublime. It is a perfectly proportioned balance of bitter, sweet, and strong—a spotlight and a stage on which liquor is the star.

Among its virtues is that it can easily be made at home. I use a rich, brown Demerara syrup, two different brands of aromatic bitters, and a spicy, oaky bourbon like Buffalo Trace or Eagle Rare. After a day of staring at a computer screen, the process of measuring, pouring, and then stirring—with a long spoon, the bowl turned inward so as to circulate the ice but not agitate it—is calming, forcing focus on what's to come. Making an old fashioned is, in a way, as enjoyable as drinking it. It was, and is, the ideal cocktail.

It is also the ideal of a cocktail. "There are a lot of people who view the old fashioned as not exactly a drink, but as an idea, kind of a blueprint," says Robert Simonson, a writer whose 2014 book Old Fashioned: The Story of the World's First Classic Cocktail traces its history and origins. The old fashioned is the original cocktail. Throughout much of the 19th century, the word cocktail referred exclusively to early versions of the drink. It's the insight on which the entire canon of cocktails, from the Manhattan to the martini to the Sazerac to the daiquiri, is built. Embedded within its recipe are the specs for nearly every famous cocktail that followed: a careful balance of flavors, designed to showcase the most appealing qualities of its spirit base interacting with other ingredients.

In the years before 1920, the drink, which had evolved from an earlier iceless form beginning in the mid-1800s, would have looked more or less like the one described above, with aromatic bitters and perhaps a single cherry. When prepared by a serious bartender at a serious bar, the drinks were consistent and precise, with proportions carefully tweaked and measured. Often, they were accompanied by a tiny silver spoon.

But during the next 14 years, the cocktail underwent a radical transformation.

The spoon disappeared. A splash of carbonated water was added to the top, or the bottom, or both. The fruit garnish took over the drink, with handfuls of candied cherries stuffed into the glass and giant slices of orange pounded into the sugar, creating a juicy, sweet, busy concoction more like a whiskey-soaked fruit salad than a classic cocktail. The carefully measured proportions became careless pours. Instead of a precision-crafted spirit feature, the drink had become a muddled mess—a sloppy and indifferent concoction designed to disguise whiskey rather than show it off.

And for the most part, that was the way it stayed for decades, with few American drinkers knowing what they had lost.

What happened between 1920 and 1934? Prohibition. With a few exceptions, the federal government banned the sale, production, and shipment of alcohol. Bars were closed. Distilleries were shut down. What drinking remained went underground.

When Americans came to their senses, passing the 21st Amendment and repealing the nationwide booze ban, drinkers bellied up to bars and asked for one of the few cocktails they remembered: an old fashioned. What they got would have been unrecognizable 20 years prior.

"When you get to 1934," says Simonson, "it's just, bam! The old fashioned is this fruited thing. And that's the way it is everywhere." The new drink—and it was, essentially, a different drink—had become "a glass of punch. It didn't look like it had before Prohibition."

Although no one knows the precise reasons the drink changed the way it did, Simonson speculates that in the chaos following Prohibition, the recipe may have been confused with another drink, or that bartenders piled on fruit and soda in order to conceal the low quality of the liquor that was available at the time. Whatever the reason, the change was sudden and universal.

It wasn't just the old fashioned that emerged degraded and destroyed. It was the whole of pre-Prohibition cocktail culture—the knowledge, skills, craft, and supply that for decades had informed one of America's original culinary arts, and even the essential idea of the cocktail itself. In the space of a generation, the entire country went from inventing the cocktail as we know it to forgetting how to make a decent drink.

A Great Way to Start the Day In the century before Prohibition, cocktail creation—otherwise known as bartending—was an art and an industry, part entertainment, part craft, part rebellious social signifier.

When the first iterations of American cocktails appeared in the early 1800s, they were a fixture of male counterculture. "Cocktails were in the realm of sporting men," Ted Haigh writes in Vintage Spirits and Forgotten Cocktails, "and by sporting men I mean gamblers, hustlers, and proteges of loose women." They were frequently spiked with bitters, which were originally considered medicinal, and they were consumed in the morning in order to help ease the pain of the previous evening's drink. In other words, they were eye openers and hangover cures, designed to go down easy after a hard night out while setting up the day's activities.

Even the easygoing morning drinks of the 19th century were stiff creations built around strong liquor. Take the "morning glory fizz," which involved two ounces of scotch, several dashes of absinthe, and a mixture of sugar, egg white, and citrus juice, chilled over ice. The drink, reproduced from an 1882 bartending manual by cocktail historian David Wondrich in his 2007 book Imbibe!, was originally described as "an excellent one for a morning beverage, which will give a good appetite and quiet the nerves." A few, taken in rapid succession, might end the day before it began.

Cocktails quickly developed a reputation as drinks for scoundrels and men of low character. Almost as soon as American bartenders began making cocktails, social agitators began protesting them as a blight on the national character. In 1842, after the temperance advocate Charles Jewett visited a bar with a long list of topically named drinks, he accused bartender Peter Brigham of "destroy[ing] the peace of families, the hopes of parents, the health and lives of your fellow citizens, and the souls of men." According to Wondrich, whose book recounts the episode, Brigham responded by developing a drink called the "moral suasion," named for the argumentative approach that early temperance advocates hoped would turn men of good conscience against drink. The technique didn't work, but the drink apparently did: It was quickly put on menus across the country. (Sadly, the original recipe has since been lost.)

Pre-Prohibition bartenders, in other words, were a clever, cantankerous bunch: They responded to the temperance crowd in part through their continued existence and in part through their menus. (Another creation, "the fiscal agent," also became popular.) So began a long liquid conversation between those who purveyed alcohol and those who would restrict it.

But they had more to offer than snarky drink names. The bartenders of the 19th and early 20th centuries were innovators, artists, and entertainers. They were celebrities and community pillars who used the tools of their time to create a culinary experience that was new in the world. The story of American drinking culture before Prohibition is a story of technology, branding, and market innovations.

The most important of these innovations was ice, which became widely available starting in the 1830s. The earliest cocktails were just room-temperature mixes of alcohol and other ingredients. But ice, which had previously been available only to the rich and privileged, turned cocktails into a cool, affordable luxury. It helped chill the drink—important during hot summer days decades before air conditioning or refrigeration—but was also an ingredient unto itself. Ice was shipped around the country in massive blocks chipped from lakes, and discerning bartenders preferred certain water sources for their supply. And with good reason: Those giant blocks were then chipped into large hunks, a single one of which could overwhelm a glass. The large hunks meant that the ice melted slowly, increasing the dilution of the drink and in the process tempering its character. The cut and character of the ice, and the flavor it imparted, was nearly as important to the drink as the booze.

With ice came an inventory of new tools for cutting and chipping, as well as glasses for mixing and stirring. Early bartenders were not just boozehounds; they were gearheads. They found new uses for common kitchen equipment, turning ordinary glasses into measuring cups and mixers, and they developed standards for new vessels that were not yet common. They also built new tools, like spring-rimmed strainers and accurately measured two-sided jiggers, to assist them in their efforts. The bartenders of the 19th century were driven by a spirit of competition, as well as by the practical concerns of dedicated craftsmen.

The First Celebrity Bartender Pre-Prohibition cocktails were more than just drinks. They were also a kind of a show, and the bartenders who produced and performed them could become stars.

The most prominent of these behind-the-bar stars was Jerry Thomas, author of the 1862 book How to Mix Drinks, or The Bon Vivant's Companion. Most bartenders of the time didn't write books or leave memoirs, so Thomas' book—the first collection of cocktail recipes ever published—serves as the foundational text for pre-Prohibition drink making.

Thomas, a former sailor, garnered accolades as a young man for his work at the Occidental Hotel in San Francisco, then opened a series of bars in New York, most notably a saloon on Broadway and 22nd Street. He invented or perfected dozens if not hundreds of drinks, including the spectacular, showy "blue blazer," in which fire is tossed between two mixing vessels. He helped to spread the notion that drink making was a systematic art, and he helped establish bartending as a profession and a career.

He was paid handsomely for his work, sometimes earning upwards of $100 a week, and came to New York with a $16,000 personal fortune—an astounding sum at the time. He also gambled, kept bookies in his orbit, and ran businesses into the ground.

Thomas' life veered between financial ruin and riches. He was widely known and widely loved, the subject of much media attention, more than a little of which was myth and embellishment. He was, in other words, a quintessential American figure: a man of passions and projects who charged through life on a potent mixture of luck, skill, cleverness, entrepreneurialism, inventiveness, risk, failure, success, rebellion, and rewards, not always in that order.

And he helped invent a quintessentially American product. When we speak of pre-Prohibition cocktails, what we really mean, for the most part, is drinks in the Jerry Thomas style.

Imbibe! is, in large part, an excavation of the life and drinks of Thomas, part biography, part updated recipe collection. In it, Wondrich writes that American bartenders' "facility with mixing drinks was the first legitimate American culinary art, and…the first uniquely American cultural product to catch the world's imagination." In 1920, that art would all but disappear.

Criminals, Not Craftsmen American drinking was at its zenith in the years before Prohibition. Expertly crafted cocktails could be found across the country. High-quality liquor was readily available and even, in many cases, vouched for by the government. The Bottled-In-Bond Act of 1897 set up quality standards for bottles of 100-proof liquor that were aged at federally supervised warehouses.

But on January 16, 1920, the feds officially began enforcing a blanket ban on the booze trade, with only a few exceptions. Overnight, Washington went from guaranteeing alcohol to outlawing it.

Prohibition "destroyed everything," one expert explains. Distilleries shut down and bars closed their doors. With the bars went the bartenders, and with the bartenders went the years of knowledge they had accumulated.

The immediate effect on American drinking culture was enormous. Distilleries, some of which had already moved their operations thanks to state-based prohibitions, shut down, with just a half-dozen left operating to produce alcohol for medicinal purposes. Bars closed, and skilled bartenders left the business. Common American spirits—in particular, East Coast ryes—went out of production. And foreign spirits were in many cases unobtainable.

Prohibition, says Robert Simonson, "destroyed everything. It got rid of a lot of the good spirits that we were drinking. It also forced lesser spirits to go out of existence, because they no longer had a market. Certain liqueurs and bitters—they just disappeared. It also destroyed skills. The people who were the practitioners behind the bar, they no longer had an occupation, so they had to find another way to make money, or go to another country to ply their trade. And the bars disappeared as well."

With the bars went the bartenders, and with the bartenders went the years of knowledge they had accumulated. "When Prohibition hit," says Derek Brown, who operates a fleet of cocktail bars today in Washington, D.C., "a lot of the bartenders at the height of their powers were older men."

Under the Volstead Act, bartending couldn't make you a star, or even a peaceful livelihood. It was a criminal act, and so it attracted crooks, not craftsmen.

"The older, more experienced bartenders, those who still had working life in them, got out of the business because the business during Prohibition was run by criminals," Wondrich says. "It was a nasty business."

The foundations of drink making—not just the recipes, but the technology, techniques, and theory—largely disappeared. Whether to stir or to shake, which strainers to use with which drink, how to employ gum arabic to add a silky texture to sugar syrup, the virtues of freshly squeezed juice, the nuances of flavor profiles between different bottles of bourbon and rye: The people who were the most well-versed in the craft's essential practices quit or went abroad, taking years of know-how with them.

Prohibition didn't exactly stop people from drinking. Nor did cocktails disappear completely. At least a few of the era's drinks—a tangy, sweet honey-gin-lemon concoction called "the bee's knees," a kicky absinthe-tinged sour known as the "corpse reviver No. 2″—have since been brought back (and sometimes reworked) as staples. But many Prohibition cocktails were designed to cover up liquor rather than show it off, because black market liquor was dodgy at best.

Bootleggers found ways to mimic aged hooch, or particular spirits, by using essential oils and flavor additives in a process called compounding. But even this process was sketchy, in part because Prohibition rules banned the sale and distribution of distilling guides. "During Prohibition, even the adulterants were adulterated. And that's why people got away from this stuff. So much of it was just badly done," says writer Matthew Rowley, whose book Lost Recipes of Prohibition is built around a bootlegger's secret drink manual. The results of bad booze could be dangerous, even deadly: Incidents of poisoning by sawdust liquor, which causes blindness and eventually death, became more common.

"Prohibition is often held up as the height of drinking. We all think of The Great Gatsby and speakeasies and amazing parties. But in fact, most of the drinks during Prohibition in America were pretty bad," says Noah Rothbaum, chief cocktail correspondent at The Daily Beast and author of The Art of American Whiskey. "In some ways it was close to the illegal drug trade now, I would imagine, where the origin of the alcohol during Prohibition was pretty hard to ascertain and it was cut with all types of stuff."

Under Prohibition, there was nowhere for a Jerry Thomas to thrive, and no place for the idea of cocktails as craft, career, art, and theory. The overall effect, says Simonson, was like "a nuclear bomb" on America's thriving cocktail culture. "Everything was dismantled."

"We lost so much knowledge as a society thanks to Prohibition," Rothbaum adds. "We've basically been digging ourselves out of that hole ever since."

The Dark Ages How much skill, you might wonder, does it really take to make a drink? How much knowledge could possibly have been lost? That such questions can even be asked reveals the lasting damage of Prohibition on how Americans think about drinking. One of its effects was to diminish the idea of what a bartender was. In the aftermath of Prohibition, bartending became understood as a backup gig for those with nothing else to do, not a craft and career. The drinks often reflected this understanding.

In March, I visited The Roosevelt Room, a swank but approachable bar in Austin, Texas. It's as rigorous a cocktail house as you're likely to find anywhere in the country, and it's staffed by deeply knowledgeable bartenders who will happily talk through your preferences and then build drinks to suit. The off-menu drinks they made for me included an unusual old fashioned variant using aged rum, sherry, and mole bitters, and a riff on a Negroni using a pricey Beefeater gin aged in oak barrels; Meletti, a wintry and aromatic Italian amaro; and a straw-colored gentian liqueur called Suze.

But the real draw of the bar is its massive menu, which features roughly 60 classic cocktails—an impressive selection considering that many top-tier craft cocktail venues attempt fewer than 20. The drink options are laid out on a timeline and organized by era, with selections from the early years, the turn of the century, and Prohibition, as well as a handful of Tiki drinks, post-Volstead concoctions, and modern classics. In the middle of the menu's timeline, from the 1950s through the 1990s, is a period labeled "The Dark Ages."

The drinks on that section of the menu aren't all bad—James Bond's "Vesper" is a perfectly tolerable combination of gin, vodka, and Lillet, and the "rosita" is a mix of tequila, Campari, vermouth, and bitters that will appeal to Negroni fans. All of them, too, are crafted with care. But even among this bunch of expert selections, there's a noticeable dip in the essential quality of the drinks themselves, which tend to be built around vodka and…well, vodka. The drinks aren't concerned with maintaining a sense of balance, or any coherent theory of drink design.

A sloppily constructed spirits-dumpster like a Long Island iced tea has no sensibility. At a bar like The Roosevelt Room, the drink would be carefully measured and served with freshly squeezed juice, then presented with dense, clear ice and a colorful garnish in a thoughtfully selected glass. Even in an idealized form, though, it's just an ironic wink at drinking's barbaric past.

For most of its existence, the drink—a mix of gin, tequila, vodka, rum, and triple sec that dates back to the 1970s—would have been served with sour mix, a vile substitute for fresh citrus, then slopped together in unmeasured proportions over cloudy ice, in whatever large-enough vessel might be handy. The Long Island iced tea is, at heart, little more than a crude booze-delivery system. A proper cocktail is a statement, a liquid argument, about how to drink well.

There's no getting around the fact that the latter half of the 20th century wasn't a great time for cocktails. Drinks were often boozy but overly sweet and unbalanced. Free-pouring bartenders, fearful of being labeled slow or chintzy for using jiggers, didn't worry about proportions, and high-quality liquor was rarely used, on the belief that you shouldn't waste the good stuff on a mixed drink because you couldn't taste the difference. This was a mistaken and self-defeating notion: The idea that you can't distinguish between quality tipple and bottom-shelf booze when mixed led to lots of creations that assumed low-quality liquor as given.

Even if bartenders wanted to produce more refined creations, quality spirits and bitters were difficult to find. A well-stocked bar of the era might have a few dozen bottles of alcohol plus a single container of bitters. Today's cocktail palaces frequently have hundreds of bottles of liquor and dozens of dashers of bitters.

It's not that no one tried to resuscitate the scene. "In the 1930s," Wondrich says, "there was a really determined revival." Distilleries came back online. Bartenders and liquor sellers tried to reacquire foreign imports. But those efforts were quickly stymied by the war in Europe. "Just when that got going, suddenly, you've got the fall of France, and cognac is suddenly no longer there, and all the French liqueurs. No more Holland gin," Wondrich explains. "End of 1941, we get in the war, and they stop manufacturing most liquor domestically." War, like Prohibition, was not good for cocktails. "The ingredients are no longer there. Bartenders are drafted—the young ones. The 20th century was really disruptive. After the war, there are still persistent problems with ingredients, because of the drawdown of aged spirits."

America's drinking scene struggled. Efforts to reopen distilleries or set up new ones were halting at best, in part because making spirits takes time. That's especially true with whiskey, which needs to age for several years before going to market. In the decades following Prohibition, rye whiskey, once a staple of American drinking and the base ingredient for many classic cocktails, including the Manhattan, effectively disappeared from the market.

It wasn't just Prohibition. In the middle of the century, American culture moved on as well. The postwar era brought the dawn of TV dinners and prepackaged food, which dissuaded people from such time-consuming luxuries as squeezing fresh juice. With the rise of singles bars came sweet and fruity concoctions meant as sideshows for urban bed hopping. Starting in the 1950s, Wondrich says, "everything is about convenience. Frozen ingredients, mixes—that's culture-wide, not just the bar." These changes weren't all bad for American society. But they were poison for serious cocktails.

Among its many deleterious effects, Prohibition helped destroy the idea of alcohol as a commonplace ingredient found in typical American homes. It's instructive to compare The Fannie Farmer Cookbook, published in 1896, with Betty Crocker's Picture Cook Book of the postwar era. Both were the foundational home cooking guides for their periods, but where Fannie Farmer assumes that households will have cooking sherry available, Crocker relies on a non-alcoholic sherry substitute.

In the 1950 edition, cocktails are still part of Crocker's daily routine. "The clever wife has a simple, appetizing cocktail (cold in summer, hot in winter) ready for her weary husband when he comes home at night," it says. But these cocktails are made entirely with fruit and vegetable extracts. Forgive me if I am skeptical that any weary husbands were actually calmed by a warm glass of "tomato-sauerkraut juice." Forget classical theory: During the Dark Ages, the fundamental understanding of a cocktail—a mixed drink with alcohol—had been thoroughly confused and debased.

"The drinking got dumber and dumber as we reached the '80s and early '90s," Simonson says.

Even serious cocktail connoisseurs, to the extent that they existed, had rather strange ideas about what constituted a great drink. British writer Kingsley Amis was legendary not only for his consumption of booze but for his extensive knowledge of spirits and cocktails. During the 1970s and 1980s, he wrote a widely read drinks column and several books dedicated to drinking well, all of which started from the assumption that, generally speaking, the drinking culture of the era was in poor form.

Among his favorite drinks is the old fashioned, which he argued was the only cocktail that could truly rival the martini in greatness. But Amis' recipe was a cartoonish hodgepodge: a "huge slug of whiskey" (he recommends a whopping 4 ounces), a "hefty squeeze" of orange juice, a dollop of cherry juice, a slice of orange and a cherry for garnish, plus a teaspoon of castor sugar and "as little hot water as will dissolve the sugar completely"—basically simple syrup, an ingredient he only sort of seems to grasp. Elsewhere, he describes making batches of sugar syrup with some difficulty. "Remember, you are dealing with one of the stickiest substances known," he writes before offering elaborate instructions for dealing with a gluey mess. (I can assure you that mixing equal proportions of sugar and water and then heating it together is in fact so easy and clean a process that it barely constitutes cooking at all.) Amis' bloated recipe illustrates just how far the cocktail had fallen, even among knowledgeable drinkers.

Amis was, of course, an enthusiast rather than a professional bartender. He was also, to be blunt, a drunk. But in the Dark Ages, proper cocktails were an obscure pastime for a tiny band of hobbyists, most of whom were, like 11th century monks, protecting what few scraps of imperfect knowledge remained. In the end, it was these bookish types who would return the cocktail to its proper place among America's culinary arts.

Cocktail Bookworms To understand how far the modern cocktail scene has come, and how thoroughly it has been intellectualized, consider the Columbia Room, a D.C. establishment owned by Derek Brown. In July, it won the Spirited Award for Best American Cocktail Bar—one of the cocktail world's highest honors, bestowed at the Tales of the Cocktail festival in New Orleans. It is a shrine to the art and study of mixing perfect alcoholic drinks, and it is a testament to how much American cocktails have advanced.

I visited in May to interview Brown, who in addition to owning the bar serves as chief spirits adviser to the National Archives, the first person ever to hold that title. Over the course of our conversation, he offhandedly referenced a library's worth of bartenders and books, explaining their outlooks and influence and contextualizing them both in their own time and in their relationship to our own. Brown, in other words, treats mixology as much like an academic as a bartender.

And yet the Columbia Room's drinks, while refined and even brainy, are not unapproachable. After passing through the casual outdoor Punch Garden, I sat down with Brown in the main bar area, dubbed the Spirits Library. I ordered a "Jack Rosa," a playful adaptation of the "Jack Rose," a shaken standard from the early 20th century made with apple brandy, lime, bitters, and grenadine. The Columbia Room's version adds Granny Smith apple and a delicately smoky single-village mezcal, as well as fenugreek leaf, which imparts a subtle savory spice to the drink. Drinking the Rosa, you get the sense that the original drink has been broken down, studied, and then rebuilt in a way that retains its fundamental characteristics while adding new twists and turns. It's a witty exercise in culinary deconstruction—a loving remake of a classic that also has something original to say.

Later, Brown took me into the Tasting Room, where the bar's showcase drinks are served. The entrance is hidden away in the back of the bar, and the room itself is cloaked in heavy black curtains that dampen the already dim lighting. Visible on the bar are a host of tools—everything from ornate mixing glasses to an oversized cobbler shaker to a knotty wooden swizzle stick used for making a particular family of icy Caribbean concoctions. Behind the bar is a massive tiled mural, which features plants, animals, and the names of influential historical bartenders. Brown has said that the mural depicts the story of the Columbia Room in some encrypted, metaphorical form. The space feels monastic, worshipful, intense: the holiest of holies, the deepest sanctum of cocktail art and ritual.

Brown had to leave, but he introduced me to the bartender on duty, Jake Kenny. As the bar filled up for the evening, we discussed his work. Each of the themed menus, which shift throughout the year, require months of research and development, he told me. It's a painstaking process of designing, selecting, and refining both the drinks themselves and the daily preparations necessary. He described a recent trip to France, where he spent days touring several Bas Armagnac distilleries, learning the origins and particulars of different expressions of the brandy variant. As with the celebrity bartenders of old, it's all part of the show. Listening to him describe the processes and flavor profiles of the different Armagnacs is like listening to a senior fellow at a think tank devoted to the study of booze. Later that week, he told me, he'd be teaching a class on Armagnac.

At some point he asked if I wanted another drink, and I requested something using the spirit we'd been discussing. He thought for a moment, nodded, and left the room several times to fetch ingredients, building an arsenal of alcohol on the bar.

Eventually he produced a small brown drink served with no ice in a low rocks glass. It was rich and gently bitter, with a lightly herbaceous nose and a funky sweetness offset by the tiniest hint of salt. It was delicious.

The drink turned out to be an end-stage riff on the rye-based New Orleans cocktail known as the Sazerac. This version, dubbed the "Parisian Sazerac No. 2," is made with Bulleit Rye, Dartigalongue Hors d'Age Bas Armagnac, a hint of rich simple syrup infused with roasted star anise, Peychaud's and Angostura bitters, salt tincture, a mist of green Chartreuse, and oils expressed from a lemon peel. As another bartender explained to me afterward, it was based not on the original Sazerac but on a French adaptation that Kenny further modified, making it "a variation on a variation on a variation."

Three decades ago, no bar in America would have attempted a drink like this. It would have been impossible, because not all of the ingredients would have been available. And the underlying theory, which involves splitting the base of an established classic between two spirits that work in tandem, had not yet been widely developed. The drink was only possible in the wake of the cocktail revolution, and it merely hinted at the depths and complexity now available.

Later, after I offered my compliments on the drink, Kenny apologized that it took so long to prepare. "This bar," he said, "isn't set up to serve simple drinks."

The Columbia Room is theatrical and erudite even by the standards of the most ambitious modern cocktail bars. But even in more laid-back establishments, the same sort of ritualized and intellectualized engagement with cocktails often prevails. At cocktail havens like Anvil Bar and Refuge in Houston, bartenders must memorize dozens or hundreds of drink recipes, must be able to blind taste spirits accurately, and must pass tests on weekly reading assignments. Today's bartenders had to recover the foundations of their craft almost from scratch. In the early days of the cocktail boom, especially, that meant a lot of time poring through old books, and their approach and aesthetic reflects that study. "Bartenders," Simonson says, "are the biggest bookworms."

Rotgut Renaissance Prohibition ended in 1934, but its effects lingered for decades. In some ways it still lingers, because state governments retain heavy control of the liquor market. "There are many states," Wondrich notes, "where the cocktail revolution is much more iffy because they just can't get the ingredients."

But over the last 20 years, American cocktail culture has staged a stunning comeback. The current boom started in the 1990s, when a handful of New York–based bartenders began studying old Jerry Thomas recipes and bringing back pre-Prohibition rigor, and it coincided with a parallel boom in craft whiskey and other spirits. American whiskey sales rose 37 percent between 2000 and 2013, according to the Distilled Spirits Council of the United States.

While the results of the cocktail renaissance are most obvious at bars like the Columbia Room, it has elevated more ordinary drinking as well. It's now common to find neighborhood bars that make margaritas with fresh juice and Manhattans with rye instead of bourbon. Hotel bars that once might have stocked just a handful of basic spirits now have libraries of amaro. Weddings have signature cocktails, and sometimes they're not even vodka-based. Cosmopolitans are out, and variations on "the last word" are in. In the space of a decade, the cocktail resurgence, which started with the recovery of 19th century drinks, has become a full-blown national revival, with serious cocktail houses opening in nearly every major city, major conferences and industry events emerging, and an army of slightly tipsy home enthusiasts taking up the cause.

Indeed, my own interest in cocktails comes as much from paging through recipe books and making drinks for guests as from ordering drinks at bars: Thanks to guides published by influential bars and bartenders, I can sample drinks from establishments across the country without having to travel. Yet as I have shaken and stirred my way through ever more complex libations, I have often wondered: Why did it take so long?

One reason is basic economics: America is far richer now than it was 40 years ago, or 40 years before that. The current array of pricey spirits—the Bas Armagnac in the Sazerac variation I had at the Columbia Room runs upward of $50 a bottle, and individual drinks at many cocktail bars are priced at $15 or more—is only possible in a wealthy society. Another, related reason is that this is the endpoint of a slow-moving post–World War II progression, in which Americans discovered the joys of great and varied food, and then wine, and then beer, and finally craft liquor and mixed drinks. "The culinary revolution had to proceed by steps," says Simonson. Spirits and cocktails were last.

The economy's recent tumult may have contributed as well, as educated folks gave up looking for traditional jobs. Columbia Room head bartender J.P. Fetherston has master's degrees in history from the University of Edinburgh in Scotland and the London School of Economics. "After the recession," says Brown, "a lot of people who were very smart became bartenders."

The internet also played a role, by helping early cocktail enthusiasts form a close-knit community and by creating a reservoir of easily accessed knowledge for those, like me, who followed. It helps that the extravagant presentation of many modern drinks plays well on social media. The result is a generation of cocktail culture devotees. "It's become the drug of the millennials," Wondrich says.

But the cocktail revolution might be not just a product of the digital age but a reaction to it. Online living can be overwhelming, exhausting, automated, incorporeal, and impersonal—everything that a lovingly crafted cocktail is not.

Cocktails are drinks for an era of individualism and personal preference. "That's a big part of this," Wondrich says. "That you go, and you sit at the bar, and you watch the bartender make you a drink. You can customize it if you want. You can ask for this, you can ask for that. There's a ritual, a community. You go into a good cocktail bar, people's phones are facedown on the bar. They're not all connected. They're talking to each other. It's pretty civilized. I think it fills a real need."

A great cocktail, then, is both a rite and a respite, a reminder of the pleasures of the physical realm and a salve for the anxieties of the digital age. It is an antidote for social media ennui and a form of temporary escape. Embedded in it is the ideal of balance, of bitter and sweet and strong, properly proportioned. As much as any drink, it is that idea, as simple and timeless as the old fashioned itself, that we almost lost.