White Oak trees are grown all over the United States, giving American Coopers an abundant supply of wood to make barrels. American Oak is strong and resistant to splitting thanks to its straight wood grain. This allows the staves to be split by machine, making American Oak Barrels relatively cheap produce (compared to hand-cut French Oak staves).
American Oak barrels have a strong impact on flavour and give Whisky sweeter vanilla, caramel, and brown sugar flavour— compared to aging in European or French Oak.
The American Whiskey industry churns through new oak barrels due to their requirement to use virgin or new oak barrels, resulting in an excess of ex-bourbon and ex-rye barrels for use in the wine and whisky second fill market.