Blended whiskey came into prominence in the United States during world war II, when distillers made the most of their dwindling stocks of whiskey by mixing them with unaged grain-neutral spirits. By U.S. law, blended whiskey must contain at least 20% straight whiskey. The rest may be unaged grain neutral spirits, pure alcohol with little or no flavor-and that's exactly what the cheaper, inferior blends tend to be. Actually, there are two types of blended whiskey: the aforementioned cheaper brands in which straight whiskey is blended with grain neutral spirits, and those in which straight whiskeys of varying character and qualities are blended together to produce a distinctive product. Most Scotch, Bourbon, Canadian, rye, and Irish whiskeys currently on the market, including the very best available, are blended whiskeys and fall into this second category.