Bourbon whiskey /bɜːrbən/ is a type of American whiskey: a barrel-aged distilled spirit made primarily from corn. The name is derived from the French Bourbon dynasty, although it is unclear precisely what inspired the whiskey's name (contenders include Bourbon County in Kentucky and Bourbon Street in New Orleans). Bourbon has been distilled since the 18th century. The use of the term "bourbon" for the whiskey has been traced to the 1820s, and the term began to be used consistently in Kentucky in the 1870s. While bourbon may be made anywhere in the United States, it is strongly associated with the American South, and with Kentucky in particular. As of 2014, the distillers' wholesale market revenue for bourbon sold within the U.S. is about $2.7 billion, and bourbon makes up about two-thirds of the $1.6 billion of U.S. exports of distilled spirits. The origin of bourbon is not well documented. There are many conflicting legends and claims, some more credible than others. For example, the invention of bourbon is often attributed to Elijah Craig, a Baptist minister and distiller credited with many Kentucky firsts (e.g., fulling mill, paper mill, ropewalk) who is also said to have been the first to age the product in charred oak casks, a process which gives bourbon its reddish color and distinctive taste. Across the county line in Bourbon County, an early distiller named Jacob Spears is credited with being the first to label his product as Bourbon whiskey. Spears' home, Stone Castle, warehouse and spring house survive; one can drive by the Spears' home on Clay-Kiser Road. Although still popular and often repeated, the Craig legend is apocryphal. Similarly, the Spears story is a local favorite, rarely repeated outside the county. There likely was no single "inventor" of bourbon, which developed into its present form only in the late 19th century. Essentially any type of grain can be used to make whiskey, and the practice of aging whiskey and charring the barrels for better flavor had also been known in Europe for centuries. The late date of the Bourbon County etymology has led Louisville historian Michael Veach to dispute its authenticity. He proposes that the whiskey was named after Bourbon Street in New Orleans, a major port where shipments of Kentucky whiskey sold well as a cheaper alternative to French cognac. Distilling probably was brought to present-day Kentucky in the late 18th century by Scots, Scots-Irish, and other settlers (including English, Irish, Welsh, German and French) who began to farm the area in earnest. The spirit they made evolved, and became known as bourbon in the early 19th century due to its historical association with the geographic area known as Old Bourbon (this consisted of the original Bourbon County of Virginia as organized in 1785, a region that included much of today's Eastern Kentucky – including 34 of today's counties in Kentucky). This area included the current Bourbon County of Kentucky, which became a county of Kentucky when Kentucky was separated from Virginia as a new state in 1792. When American pioneers pushed west of the Allegheny Mountains following the American Revolution, the first counties they founded covered vast regions. One of these original, huge counties was Bourbon, established in 1785 and named after the French royal family. While this vast county was being carved into many smaller ones, early in the 19th century, many people continued to call the region Old Bourbon. Located within Old Bourbon was the principal port on the Ohio River, Maysville, Kentucky, from which whiskey and other products were shipped. "Old Bourbon" was stencilled on the barrels to indicate their port of origin. Old Bourbon whiskey was different because it was the first corn whiskey most people had ever tasted. In time, bourbon became the name for any corn-based whiskey. Although many distilleries operated in Bourbon County historically, there were no distilleries operating there between 1919, when Prohibition began in Kentucky, and late 2014, when a small distillery opened – a period of 95 years. A refinement often dubiously credited to James C. Crow was the sour mash process, by which each new fermentation is conditioned with some amount of spent mash. Spent mash is also known as spent beer, distillers' spent grain, stillage, and slop or feed mash, so named because it is used as animal feed. The acid introduced by using the sour mash controls the growth of bacteria that could taint the whiskey and creates a proper pH balance for the yeast to work. A concurrent resolution adopted by the United States Congress in 1964 declared bourbon to be a "distinctive product of the United States" and asked "the appropriate agencies of the United States Government... [to] take appropriate action to prohibit importation into the United States of whiskey designated as 'Bourbon Whiskey.'" Federal regulation now defines "bourbon whiskey" to only include "bourbon" produced in the United States. In recent years, bourbon and Tennessee whiskey (which is sometimes regarded as a different type of spirit but which generally meets the legal requirements for being called bourbon) have enjoyed significant growth and popularity. The Distilled Spirits Council of the United States, the industry trade group, tracks sales of bourbon and Tennessee whiskey together. According to the Distilled Spirits Council, during 2009–14, the volume of 9-liter cases of whiskey increased by 28.5% overall. Higher-end bourbon and whiskeys experienced the greatest growth: during 2009–14 the volume of the value segment increased by 12.1%, premium by 25.8%, high-end premium by 27.8% and super-premium by 123.8%. Gross supplier revenues (including federal excise tax) for U.S. bourbon and Tennessee whiskey increased by 46.7% over the 2009–14 period, with the greatest growth coming from high-end products (18.7% growth for value, 33.6% for premium, 44.5% for high-end premium, and 137.2% for super-premium).[4] In 2014, more than 19 million nine-liter cases of bourbon and Tennessee whiskey were sold in the U.S., generating almost $2.7 billion in wholesale distillery revenue. U.S. exports of bourbon whiskey surpassed $1 billion for the first time in 2013; distillers hailed the rise of a "golden age of Kentucky bourbon" and predicted further growth. In 2014, it was estimated that U.S. bourbon whiskey exports surpassed $1 billion (making up the majority of the U.S. total of $1.6 billion in spirits exports). Major export markets for U.S. spirits are, in descending order: Canada, the United Kingdom, Germany, Australia and France. The largest percentage increases in U.S. exports were, in descending order: Brazil, the Dominican Republic, Bahamas, Israel and United Arab Emirates. Key elements of growth in the markets showing the largest increases have been changes of law, trade agreements, and reductions of tariffs, as well as increased consumer demand for premium-category spirits.