It may come as a bit of a surprise, with the exception of some microdistilleries who produce single malt whiskey (with an 'e') for local markets, but technically all American whiskey is blended whiskey, even Bourbon. However, there is a huge difference with Scottish blends. Where the Scots blend different distillates from different grains after maturation, the American distillers blend the grains before distillation and then mature the 'white dog', as new-make spirit is called in the USA.
This is how it works. American whiskeys are mostly made of a mixture of different grains, following a specific recipe called a 'mash bill' in the trade. Predominant grains are corn, rye, wheat and malted barley. Every distillery in the USA uses its own recipes. And remember, not all American whiskey is Bourbon, but all Bourbons are American whiskey.
Most whiskeys in the USA are distilled in two rounds. The first one in a continuous still, here called the 'beer still'. The second distillation takes place in either a 'thumper' or 'doubler', the latter more closely resembling a pot still. There is one exception to the rule: Woodford Reserve Bourbon, which is distilled three times in copper pot stills, manufactured by Forsyth's in Rothes, Scotland. This is unique in the Bourbon industry.
We can distinguish five main types of whiskeys made in the USA.
In short, Bourbon, may be made anywhere in the USA. The lion's share is made in Kentucky. Bourbon needs to be made from at least 51 per cent corn, with the addition of rye, wheat and/or malted barley. Generally speaking the more rye is added, the spicier the Bourbon. More wheat mellows the Bourbon. Only a small percentage of malted barley is added as a catalyst to form enzymes that will convert starch into sugar. Well-known brands are Four Roses, Maker's Mark, Wild Turkey and Jim Beam.
Can only be made in the eponymous state. This is the only region-specific adjective used in the USA. This type of whiskey usually has a higher proportion of corn than Bourbon has. Furthermore the new distillate, white dog, is filtered through sugar maple charcoal before maturation. Well-known brands are Jack Daniel's and George Dickel.
Also primarily made in Kentucky, needs to have at least 51 per cent rye at its core, with the addition of corn, wheat and/or malted barley. Well-known brands are Old Overholt, Rittenhouse, George T. Stagg and Sazerac. In rye whiskeys the spicy taste is more pronounced.
Should contain at least 51 per cent wheat on the mash bill. This variety is rather rare. A good example is Bernheim's.
As more than 80 per cent corn on the mash bill. Platte Valley is a nice example. This type of whiskey is colourless, very sweet, oily and syrupy. Blended whiskey predominantly consists of neutral grain alcohol with small additions of Bourbon or rye whiskey to flavour the drink. A well-known brand is Barton's. This type of whiskey is more suitable for long drinks, such as a whiskey soda.
The Republic of Ireland
The Irish predominantly make blended whiskey and use pot stills as well as column stills. Good examples are Jameson and Paddy. Confusingly Kilbeggan is bottled as a blended whiskey but also as a single grain whiskey. A special type of blended whiskey indigenous to Ireland is pure or single pot still whiskey, distilled from a mixture of malted and unmalted barley, using a copper pot still. Well-known brands are Redbreast and Green Spot. A mixture of blend, grain and pure pot still whiskey can also be found, for instance Tullamore DEW.
In Northern Ireland, Bushmills Distillery known for its triple distilled eponymous single malt, also produces the blended whiskey Black Bush. In the last couple of years the number of distilleries in both countries has grown from four to over a dozen. The new kids on the block are mostly small craft distillers and their products range from vodka and un-aged rum to, sooner or later to be bottled, whiskey. Whether that will be blends, single malts, or a combination thereof remains to be seen.
India is by far the largest producer of blended whiskey in the world with an annual production over 1 billion litres of potable alcohol. The container name is Indian Made Foreign Liquor (IMFL), but we have to take this with a pinch of salt. IMFL captures a range including whisky, brandy, rum, gin and vodka. Most output would not even be considered straight whisky by the Western world. Indian distillers use the following raw materials to distil from: barley, molasses, corn, rice, bajra and sorghum. This is how it works: Extra Neutral Alcohol (ENA) is distilled from sugar cane in column stills, then blended with indigenous whisky or imported Scotch. The following four types are distinguished: Economy, Regular, Prestige, and Premium. Economy is ENA with flavourings, Premium is made and aged similarly to single malt Scotch and the two between are a blend of Indian and Scotch malt whiskies, ENA and flavourings. The most well-known brand names are Officer's Choice and McDowell's No. 1.
Due to the space available only a small selection per continent is mentioned. Production methods vary, from emulating the Scottish model to using hybrid column/pot stills, known as Charentais stills in the trade. Most European distilleries produce a variety of whiskies, experiment with different wood regimes and use other types of grain, such as buckwheat and spelt. It is not always easy to classify these whiskies as blend, single malt or 'alien'. Just to name a few: The Czech Republic produces a blend called Gold Cock and claims to have been in production since 1877. Arcus in Norway produces the blend Gjoleid, made from a mix of corn and wheat, not unlike a mellow Bourbon. The Lakes Distillery in England markets a blended whisky called The One. Destilerías y Crianza in Spain produces a tasty blend called DYC, resembling a light Speysider. The Distell Group is the largest producer in South Africa, with the brand Three Ships, available as a blend and as a single malt. Last but not least Australia has seen a true revival of the craft, mostly in Tasmania, consisting of distilleries that may produce both malts and blends. Well-known brands are Lark and Overeem.