There’s no law mandating that bourbon must be produced in Kentucky, although it might seem that way given the state’s dominance in distilling the distinctive corn-based, barrel-aged whiskey. According to the Kentucky Distillers’ Association, the Bluegrass State produces and ages approximately 95 percent of the world’s bourbon whiskey.

So is there something in Kentucky’s water that has caused the bourbon industry to flourish? In fact, there is. The state sits atop vast deposits of blue limestone, which filters out hard iron and imparts sweet-tasting calcium and magnesium. “To this day you can go to an open stream in Kentucky, and it will taste better than 90 percent of tap water in the country because the limestone filters out unwanted minerals,” says whiskey historian Fred Minnick, author of “Whiskey Women” and “Bourbon Curious: A Simple Tasting Guide for the Savvy Drinker.”
Kentucky’s wide temperature swings—from chilly winters to hot summers—are also conducive to producing bourbon because they cause the charred oak barrels, which give the spirit its amber color and distinctive taste, to alternately absorb and release the whiskey. “We have the ideal climate to age bourbon probably,” says Wild Turkey master distiller Jimmy Russell, a member of the Kentucky Bourbon Hall of Fame who grew up less than five miles from the distillery where he has worked since 1954. “You need the hot summers and cold winters so that the wood can breathe and the whiskey can move in and out of it.”

Another factor that makes Kentucky fertile ground for bourbon production is literally its fertile ground. The influx of settlers who crossed the Appalachian Mountains in the late 1700s soon learned the Kentucky soil was perfect for growing bourbon’s second main ingredient—corn. Drawn in part by Virginia’s 1776 Corn Patch and Cabin Rights Act, which offered 400 acres to any settlers who built cabins and planted corn in its then-territory of Kentucky, immigrants from Germany, Scotland and the north of Ireland were among those who arrived with the whiskey-distilling knowledge from their homelands in tow.

The ease of growing corn in Kentucky caused distillers who migrated from the East Coast to change their whiskey recipes. “Rye was the plentiful grain in Pennsylvania and Maryland,” Russell says, “but when distillers came over the Appalachians they found corn the dominant grain so they used corn instead of rye.”

By the 1780s a distinctive style of corn-based whiskey was being distilled in Kentucky, although Minnick says the story that Baptist minister Elijah Craig invented bourbon by accident after storing his whiskey in barrels charred by a fire is mere legend concocted by whiskey advocates to cloak the spirit in the spiritual. “Craig was a very powerful and important person, but we don’t have any credible records to indicate that he would have been a true inventor of bourbon,” Minnick says.

Whiskey increased in popularity after the American Revolution as the import of rum—which had been the most popular alcoholic drink in many American colonies—slowed with decline of the “triangle trade” with Great Britain. The lingering debt from the war, however, caused the federal government to levy a tax on liquor in 1791. Distillers in Maryland and Pennsylvania, in particular, bristled at the tax and led the Whiskey Rebellion, which was eventually quelled by thousands of federal troops dispatched by President George Washington in 1794.

Minnick notes, however, that the Whiskey Rebellion did not spark a mass migration of tax-dodging distillers to Kentucky and that an estimated 500 distilleries were already operating in the state at the time. However, he notes that to prevent a similar popular uprising Congress left whiskey largely tax-free until the Civil War, except briefly to pay for the War of 1812. “After the Whiskey Rebellion, Congress decided not to tax whiskey, but they added tariffs onto rum because there was a thought that money from rum would end up getting into the hands of the British.”

The high levies on rum and its key ingredient, molasses, contributed to soaring whiskey consumption in the early decades of the republic. Kentucky’s whiskey industry, in particular, thrived as slave labor assisted with production and distillers took advantage of the state’s plethora of navigable waterways—such as the Kentucky, Tennessee, Ohio and Mississippi Rivers—that provided easy access to big cities such as Cincinnati and New Orleans.

In addition to Kentucky’s geographic advantages, Minnick says the state’s strong families who passed distilling down from generation to generation and sustained their businesses in bad economic times also allowed the bourbon industry to flourish. “Many major areas had significant distilling capacity, but the stronger families were here in Kentucky, and that sustained bourbon through the years. All the historical family names that you see on these old bourbon bottles were passionate. They developed a following, and for the most part these companies have been able to work together for the common good.”

Although the term “bourbon” began to appear in newspaper advertisements for Kentucky’s particular brand of whiskey by the 1820s, its origins are murky. Some historians believe the moniker was inspired by Kentucky’s Bourbon County—itself named after the French royal family in recognition of France’s support in the American Revolution. Bourbon County originally occupied a large section of central Kentucky, and local distillers stamped its name as the county of origin on whiskey barrels transported around the country. Minnick says another theory is the name derived from Bourbon Street in New Orleans, where the drink was popular in the French Quarter saloons. “There’s not enough good evidence one way or another,” he says.

There’s one fact about bourbon, though, that can’t be disputed according to Russell. “You can make bourbon anyplace in the country,” he says, “but if it’s not Kentucky bourbon, it’s not bourbon.”