American whiskey made from a mash of at least 51% corn, with the remainder being any other grain. Rye and wheat are most common, and most contain a small amount of malted barley to aid in the fermentation process.
It must be distilled to no more than 80% ABV, aged in charred new American oak containers with an entry ABV of no more than 62.5%, and bottled at no less than 40% ABV. Bourbon may be produced anywhere in the United States. For more information, see “Instant Expert: Bourbon, Rye, and American Whiskey.”