When Prohibition was enshrined in the constitution in 1920, the attack on the industry led to serious economic consequences; distilleries were closed and jobs were eliminated for barrel-makers, restaurant wait staff and truck drivers. The government lost $11 billion in tax revenue while spending $300 million trying to enforce the Prohibition amendment.

History shows Prohibition was a failure, but not every set of laws passed by the U.S. government related to alcohol has been so useless. In addition to naming bourbon “America’s Native Spirit” in 1964, the U.S. government has watched over the bourbon production process almost since its inception.

Every time customers browse a good online bourbon selection from a Web-based store, they’re looking at a product defined by the most successful alcohol-related regulations the American government has ever passed. For whiskey to be named “bourbon,” it has to meet six specific legal requirements.

Must Be Made From a Grain Mash Containing at Least 51-Percent Corn

American bourbon producer Jim Beam calls bourbon “whiskey’s sweet spot.” Every barrel of bourbon produced is whiskey, but not every whiskey is bourbon. Whiskey distillers use different ratios of grain in their bourbon mashes.

For example, Breckinridge Bourbon Special Reserve is distilled from a mash containing 56 percent corn, 38 percent rye and 6 percent malted barley. Other bourbons replace the rye with wheat for a smoother flavor profile. However, one element of the grain mash must always be in place: It has to consist of at least 51 percent corn.

In addition to mixing and cooking corn-grain mash for bourbon, some whiskey distillers add “sour mash” to kick off the fermentation process. Sour mash has the same role as a sourdough starter for making sourdough bread. The mash and sour mash mix is combined with yeast and fermented until it’s ready to distill.

Must Be Less Than 160-Proof

All bourbon produced must reach no more than 80 percent alcohol-by-volume (ABV), or 160-proof, during the distillation process. Most bourbons fall into the 80-proof to 160-proof range, and the average bourbon rarely exceeds 130-proof.

Must Be Free From Additives During the Distillation Process

To cut the alcohol content, bourbon producers are allowed to add water during distillation. However, they can’t add anything else. As a result, the flavor of bourbon depends largely upon the barrels in which it’s aged.

Jack Daniels Tennessee whiskey is almost identical to bourbon until the end of the distillation process — when it’s filtered through maple charcoal. Because of this additive, the U.S. government doesn’t consider Jack Daniels to be bourbon.

Must Be Aged in New, Charred White-Oak Barrels

All bourbon must be aged in never-before-used barrels made of white oak. The interior of each barrel is then charred before the distilled alcohol is poured inside.

Once inside, the bourbon goes into a rick house to age inside its barrels. Most producers don’t climate-control the rick house, so different temperatures allow the barrel wood to expand and contract. Bourbon from a barrel stacked close to the ceiling will taste different from bourbon aged near the floor.

Because no barrel can be re-used, after the bourbon has finished aging many distributors ship their barrels off to Scotland, where they’re used to age Scotch whiskey or around the U.S. where they are used to store everything from coffee beans to maple syrup.

Must Be Aged for at Least Two Years

During the bourbon aging process, caramelized sugars from the charred wood seep into the alcohol within every barrel.

Part of the bourbon also evaporates from the barrel or gets absorbed into the wood. The Buffalo Trace Distillery isn’t upset by the bourbon that evaporates; a sign at the distillery reads: “We like to think it is the bit of bourbon that we are sharing with the angels.”

Must Be Made in the USA

About 95 percent of all bourbon is made in Kentucky; the state is actually home to more barrels of bourbon than people. Bourbon can be made anywhere in the U.S., but it can’t be made outside of the country. It’s “Made in the U.S.A.” origins helps bourbon live up to the title of “America’s Native Spirit.”