One reason for this strong association is the romanticized advertising in the 1990s of bourbon as a product of Kentucky with rural, Southern origins.

[3][4] Even though bourbon was strongly associated with the South, it was also a symbol of urbanization and sophistication due to a large percentage of consumers belonging to the middle- to upper-class, including business and community leaders.

[11] Distilling was most likely 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.

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 said to have been the first to age the product in charred oak casks, a process that gives bourbon its brownish color and distinctive taste.

[13] The late date of the Bourbon County etymology has led historian Michael Veach to dispute its authenticity.

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.

The acid introduced when 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.

[24][25] After the end of Prohibition at the federal level in late 1933, it continued in various places at the state, county and local level, and liquor sales are still prohibited or restricted in many jurisdictions in Kentucky, the primary bourbon-producing state (and in Tennessee as well, where Tennessee whiskey is made).

The industry trade group Distilled Spirits Council of the United States (DISCUS) tracks sales of bourbon and Tennessee whiskey together.

[10] Gross supplier revenues (including federal excise tax) for U.S. bourbon and Tennessee whiskey increased by 46.7% over the 2009–2014 period, with the greatest growth coming from high-end products.

[10] 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.

[9] Major export markets for U.S. spirits are, in descending order: Canada, the United Kingdom, Germany, Australia, and France.

[9] The largest percentage increases in U.S. exports were, in descending order: Brazil, the Dominican Republic, Bahamas, Israel, and United Arab Emirates.

[citation needed] On May 4, 1964, the U.S. Congress declared bourbon whiskey as a "distinctive product of the United States" by concurrent resolution.

[46] The filtering of iron-free water through the high concentrations of limestone that are unique to the area is often touted by bourbon distillers in Kentucky as a signature step in the bourbon-making process.

[65][66][67] The largest bourbon distiller outside of Kentucky and Tennessee is MGP of Indiana, which primarily wholesales its spirits products to bottling companies that sell them under about 50 different brand names – in some cases, misleadingly marketed as "craft" whiskey, despite being produced at a large wholesaler's factory.

[68][69] To be legally sold as bourbon, the whiskey's mash bill requires a minimum of 51% corn, with the remainder being any cereal grain.

[8] A proposed change to U.S. regulations will expand allowable "grains" to include seeds of the pseudocereals amaranth, buckwheat, and quinoa.

Most modern bourbons are initially run off using a column still and then redistilled in a "doubler" (alternatively known as a "thumper" or "retort") that is basically a pot still.

[73] The resulting clear spirit, called "white dog", is placed in charred new oak containers for aging.

In the mid-2010s, some sources began referring to these as "hazmat" bourbons, alluding to the ban in the U.S. Code of Federal Regulations on air travel passengers and crew members carrying such high-proof beverages due to their highly flammable nature.

Although only the focus of special attention for bourbon since the mid-2010s, very-high-proof products are not especially novel in general, as evidenced by the well-known Bacardi 151 brand of rum, which was available on the U.S. and Canadian markets from about 1963 until 2016 and was bottled at 75.5% ABV.

[82] They may not be reused for bourbon, and most are sold to distilleries in Canada, Scotland, Ireland, Mexico, and the Caribbean for aging other spirits.

[83] The bottling operation for bourbon is the process of filtering, mixing together straight whiskey from different barrels (sometimes from different distilleries), diluting with water, blending with other ingredients (if producing blended bourbon), and filling containers to produce the final product that is marketed to consumers.

Various other countries have trade agreements with the U.S. to recognize bourbon as a distinctive product of the U.S., including Canada and Mexico, the United Kingdom, Chile, and Brazil.

To test this theory, Jefferson's cofounder Trey Zoeller sent two barrels of the company's signature product to New York City via barge, first down the Ohio and Mississippi Rivers and then along the Intracoastal Waterway.

According to Popular Mechanics writer Jacqueline Detwiler-George, who documented the test, the sample that made the waterborne journey "was mature beyond its age, richer, with new flavors of tobacco, vanilla, caramel, and honey.

It was theorized that the action of gentle sloshing of the whiskey in barrels for a period of 2 to 4 weeks during the barge trip led to a dramatic improvement in smoothness and taste.