What Is Bourbon? A Complete Guide to America’s Native Whiskey
Learn what bourbon is, how it’s made, and what makes it different from other whiskey.
What Is Bourbon? (Quick Answer)
Bourbon is a type of American whiskey made from at least 51% corn and aged in new, charred oak barrels. To be called bourbon, it must be produced in the United States and contain no added flavours or colouring.
To legally be called bourbon, it must:
- Be made in the United States
- Contain at least 51% corn
- Be aged in new charred oak barrels
- Be distilled to no more than 80% alcohol
- Be entered into the barrel at no more than 62.5% alcohol
- Contain no added flavoring or coloring
In short:
Bourbon = American whiskey made mostly from corn, aged in new oak barrels. These requirements are defined under U.S. federal regulations for distilled spirits.
What Makes Bourbon Different from Whiskey?
All bourbon is whiskey, but not all whiskey is bourbon.
How to taste Whisky | A beginners guide
We've put together a complete guide to tasting whisky, find it by clicking the button below.
What Does Bourbon Taste Like?
Bourbon is typically sweeter and richer than many other whiskies.
Common flavour notes include:
- Vanilla
- Caramel
- Toffee
- Oak
- Spice (especially from the barrel)
- Dried fruit
The high corn content gives bourbon its characteristic rounded sweetness, while the charred oak barrels add depth and structure.
How Is Bourbon Made?
The bourbon-making process follows a clear set of steps.
1. Mash Bill (Grain Mix)
The mash must contain at least 51% corn.
The rest is usually a mix of:
- Rye (adds spice)
- Wheat (adds softness)
- Malted barley (helps fermentation)
What Is Sour Mash?
Most bourbon is made using the sour mash process, where a portion of a previous distillation is added to the next batch. This lowers the pH and creates a more stable environment for fermentation. The result is greater consistency in flavour and quality across batches. Despite the name, sour mash does not make the bourbon taste sour, it simply helps control the fermentation process.
2. Fermentation
The grains are mashed and mixed with water and yeast.
Yeast converts sugar into alcohol
This creates a low-alcohol liquid called “distiller’s beer”
3. Distillation
The liquid is distilled to concentrate alcohol and flavour.
Typically done in column stills.
Sometimes followed by pot still refinement.
4. Aging in New Charred Oak Barrels
This is where bourbon develops most of its character.
Barrels must be new and charred inside
Aging happens naturally over time
No minimum aging is required for bourbon, but:
“Straight bourbon” must be aged at least 2 years
How Climate Affects Bourbon Aging
Bourbon matures in warehouses where it is exposed to natural temperature changes. In Kentucky, hot summers cause the spirit to expand into the oak, while colder winters pull it back out again. This repeated expansion and contraction accelerates the interaction between wood and spirit. Compared to cooler climates, this leads to faster extraction of colour and flavour, which is why bourbon often develops rich notes in fewer years than some other whiskies.
5. Bottling
Before bottling:
Bourbon may be diluted with water
No additives are allowed
Why Are New Oak Barrels Important?
Unlike many other whiskies, bourbon must use new barrels every time.
This gives bourbon:
- Strong vanilla and caramel notes
- Deep colour
- Faster flavour development
It’s also why used bourbon barrels are later reused worldwide (for example in Scotch whisky production).
Bourbon must be aged in new, charred oak barrels, and this has a direct chemical impact on flavour. When the inside of the barrel is charred, it breaks down compounds in the wood into sugars and flavour molecules such as vanillin and caramelised compounds. As the spirit ages, it extracts these elements, creating the characteristic notes of vanilla, caramel, and toasted oak. Using new barrels ensures a strong and consistent flavour profile that defines bourbon.
Many of these principles are not unique to bourbon. At Copenhagen Distillery, we apply similar approaches when working with grain, fermentation, and barrel ageing, where small changes can have a significant impact on flavour.
- Explore the options here
Where Is Bourbon Made?
Bourbon can legally be made anywhere in the United States.
However, around 95% of all bourbon is produced in Kentucky, thanks to:
- Climate (hot summers, cold winters)
- Limestone-filtered water
- Long distilling traditions
Is Bourbon Always Made in Kentucky?
No.
A common myth is that bourbon must come from Kentucky.
In reality:
It must be made in the USA
Kentucky is simply the dominant region
Bourbon vs Scotch vs Whiskey
If you’re comparing categories:
- Bourbon → American, corn-based, sweet
- Scotch → Scottish, barley-based, often smoky
- Whiskey/whisky → broad category covering all styles
If you want a full breakdown, see:
→ Bourbon vs Scotch vs Whisky: What’s the Difference
How to Drink Bourbon
Bourbon is versatile and can be enjoyed in several ways:
- Neat – to experience full flavour
- With a splash of water – opens aromas
- On the rocks – slightly diluted and chilled
- In cocktails – e.g. Old Fashioned, Manhattan
How is Whisky made | a detailed guide
If you want to learn more about Whisky Production you can find the article here.
The History of Bourbon
Bourbon is often called America’s native spirit, and its story is closely tied to early American agriculture and immigrant distilling traditions, particularly in the late 18th century.
Bourbon Timeline
1700s – European settlers arrive
- Scottish, Irish, and German immigrants bring distilling traditions to North America
- Early whiskey is mostly made from rye and barley, like in Europe
Late 1700s – Corn becomes dominant
- In Kentucky and surrounding regions, corn grows more easily than other grains
- Distillers begin using corn as the primary ingredient
→ This shift lays the foundation for what becomes bourbon
1780s–1820s – Bourbon County and naming
- The name “bourbon” is commonly linked to Bourbon County, Kentucky
- Whiskey shipped downriver was marked “Old Bourbon”
→ Over time, the name becomes associated with the style itself
1800s – Barrel aging develops
- Transporting whiskey in charred oak barrels becomes standard
- The interaction with new wood creates:
darker colour
vanilla and caramel flavours
→ A defining characteristic of bourbon emerges - darker colour
- vanilla and caramel flavours
→ A defining characteristic of bourbon emerges
Late 1800s – Sour mash process
- Distillers begin using the sour mash method (recycling part of a previous batch)
- This improves consistency and fermentation control
→ Still widely used today
1920–1933 – Prohibition
- Legal production of alcohol is banned in the U.S.
- Only a few distilleries survive by producing “medicinal whiskey”
→ Many traditions are lost, but the category survives
1964 – Bourbon is legally defined
- The U.S. Congress declares bourbon a “distinctive product of the United States”
- Legal requirements are formalised:
minimum 51% corn
new charred oak barrels
no additives - minimum 51% corn
- new charred oak barrels
- no additives
2000s–today – Global resurgence
- Bourbon sees rapid growth worldwide
- Premium and craft bourbon categories expand
- International demand increases significantly
Why Bourbon Developed in Kentucky
While bourbon can be made anywhere in the United States, Kentucky became the center due to:
- Abundant corn crops
- Limestone-filtered water (low in iron, ideal for distilling)
- Climate variation (hot summers and cold winters accelerate aging)
- Strong early distilling communities
Today, around 95% of bourbon is still produced in Kentucky.
Popular Bourbon Brands
- Jim Beam | classic, widely available
- Maker’s Mark | wheated bourbon, softer profile
- Buffalo Trace | well-known Kentucky distillery
Below you can find a family tree of who makes what - there are a handfl of distilleries today that make almost all the brands we know and love.
FAQ: What Is Bourbon?
Is bourbon the same as whiskey?
No. Bourbon is a specific type of whiskey with strict production rules.
Why is bourbon sweeter than other whiskey?
Because it contains at least 51% corn, which gives natural sweetness.
Does bourbon have to be aged?
Yes, but there is no minimum for basic bourbon.
“Straight bourbon” must be aged at least 2 years.
Can bourbon be made outside the USA?
No. To be called bourbon, it must be produced in the United States.
What is the difference between bourbon and rye whiskey?
The main difference is the grain:
Bourbon → corn (sweet)
Rye → rye grain (spicy, dry)
Is bourbon always smoky?
No. Bourbon is typically not smoky. Smokiness is more common in some Scotch whiskies.