What is the main whiskey used in a Regular Manhattan?

The Regular Manhattan is traditionally made with Bourbon Whiskey. This classic cocktail typically combines whiskey, sweet vermouth, and bitters, and its rich flavor profile pairs beautifully with the notes found in bourbon, which is sweet and caramel-like due to the charred oak barrels used during aging.

When comparing the options, rye whiskey is another valid choice for a Manhattan but is often associated with a spicier flavor than what is typical in the classic recipe. Scotch whiskey, known for its smokiness, is not used in a standard Manhattan, as its distinctive flavors would clash with the sweetness of the vermouth. Irish whiskey, while smooth and light, does not provide the same depth and richness that bourbon does in this particular cocktail.

Therefore, when preparing a traditional Manhattan, bourbon is the preferred choice because it complements the other ingredients, resulting in a balanced and flavorful drink.