Bourbon is America’s native spirit, and also currently our most popular one. Given these facts, one might assume that to make bourbon, only newly charred American oak barrels will do, but this is a common misconception. While bourbon does need to be aged in a newly charred oak container, that oak does not need to be American, and in fact, it doesn’t even need to be in the shape of a barrel!
The TTB [Alcohol and Tobacco Tax and Trade Bureau] regulation defines bourbon as whiskey “produced in the U.S. at not exceeding 80 percent alcohol by volume (160 proof) from a fermented mash of not less than 51 percent corn and stored at not more than 62.5 percent alcohol by volume (125 proof) in charred new oak containers.”
This means that bourbon producers can use French oak, Japanese Mizuna oak, Brazilian oak, Hungarian oak — whatever kind of oak they want, and in whatever kind of container they want, be it a box, a sphere, go crazy — so long as that container is charred and first-use.
The reason for American oak being the most prevalent species used for bourbon is its availability. The spirit is made in America, after all, and it was much easier and affordable in the past to source the oak from the trees growing in the same country, rather than to buy oak shipped in from other faraway places. And as far as the shape of the container goes, the barrel is best for ensuring the ideal amount of liquid comes in contact with the wood as the spirit ages and develops its flavor.