As America took shape around the late 1700s, a large majority of immigrants with distilling knowledge arrived from Western Europe and beyond. Armed with these skills, the settlers began using European distillation techniques on New World crops and a new category of spirit was born: American whiskey. 

Entrepreneurs, like George Dickel (who arrived from Germany in 1844), rejoiced when they discovered the fertile valleys of North America, favorable to spirit production. Establishing himself in Tennessee, Dickel declared it, "a distiller's dream", due to the native limestone shelf providing sweet, pure water and the surrounding flats yielding ample grains. 

The burgeoning industry encountered its first major hurdle when, in a bid to recuperate the debt accumulated in the American Revolution, the US Government introduced a Whiskey Tax of 1791. This led to a farmer’s revolt (the Whiskey Rebellion) and caused many to relocate to tax-friendly Kentucky and Tennessee, where federal laws did not yet apply. 

When Thomas Jefferson lifted the tax in 1802, the industry really grew; whiskey production flourished nearly anywhere that had good grains and water. Distilleries with access to rivers or ports had easier distribution routes and widened their customer base considerably. 

Following the Civil War, the industry was recovering, and distillers were increasingly concerned with protecting their products and assuring quality, as some bonders and retailers added rogue ingredients for easier profits. To stop this, distillers lobbied Congress for the Bottled in Bond Act of 1897 which established compulsory regulations for producing bourbon. 

In 1920, Prohibition was passed, and all spirit production came to a halt. This marked a dark chapter in American whiskey making, with the market continuing to suffer through World War II forcing many independent distillers to close permanently. 

The current resurgence of popularity for the industry was made possible by foreign demand (and investment) and the committed efforts of a select few in North America. Many of these, like Thomas E. Bulleit Jr., who inherited a fifth-generation high rye content mash bill, were family members aiming to resurrect family legacies of the golden era. 

A steady increase in production saw the category raise itself again and in 1964, an act of congress declared bourbon as, "America's Native Spirit", officially cementing its place in US culture. 

Distillers then cook the mix, adding different grains at corresponding temperatures; corn is exposed first, mixing with water before the temperature is dropped to introduce wheat or rye. Barley enters the fold last and at the lowest temperature. 

Globally, whiskey makers are likely to blend these different spirits following distillation; Americans, however, are the only ones to cook assorted grains together. Another key difference is that, after cooking, other producers will separate the sugary liquid (referred to as 'wort') from the solids and send the wort to fermentation. In American whiskey, the entire mash (solids included) is sent to a vat where the yeast and ‘sour mash’ is added for fermentation. 

Sour mash is the leftover mash from previous distillation(s) and is quintessential to American whiskey (it is the norm to incorporate this in production, especially for bourbon), with the term derived from its sour taste.  The sour mash increases the acidity of the fermenting liquid and exterminates the undesirable actions of other bacteria present. 

The mash is then moved to distillation, with most US whiskey treated twice. Typically, most distilleries will employ a column still first before using heated copper stills to remove fusel oils and further impurities. The second distillation may happen in a doubler (small pot still) or a Thumper (a retort that resembles a small pot that is half filled with water, spirit tails from a previous batch, or even whiskey). The resulting new spirit known as 'White Dog', can be distilled up to 80% ABV but normally at around 70% ABV, is then transported to the cooperage to instigate the barrel aging process. 

At this stage, Tennessee whiskey is required to undergo maple charcoal filtration before aging. This is known as the Lincoln County process (LCP) and is the legal legislation that demarcates Tennessee whiskey from Bourbon. The LCP removes hardness and makes the spirit smoother in texture.