Applejack is an alcoholic beverage made from apples. It goes back to the time when the United States was still an English colony. It is produced from the raw must concentration by fractional distillation at very low or hot temperature.
The term apple “jack" comes from...
...jacking, the popular name for distillation.
From the fermented juice with an alcohol content of less than 10% a concentrate is obtained with an alcohol content of 30 to 40%, slightly sweetened, which usually has the taste and smell of apples. Due to the relatively higher cost and lower yield of alcohol produced from fruit fermentation, products commercially called applejack may consist of apple juice with added grain brandy until the spirit reaches the desired alcohol content.
Applejack is linked to the history of New Jersey, it was used as a mean of payment for road construction teams in the 18th century. The oldest distillery in America is Scobeyville, Laird & Co apple jack producer in New Jersey (see below in turquoise colour).
Applejack can also refer to a cocktail based on apple liqueur and whisky "Jack Daniel's".
Apple cider (also called sweet cider or soft cider or simply cider) is the name used in the United States and some parts of Canada for an unfiltered, unsweetened, non-alcoholic beverage made from apples. Although it is generally simply called "cider" in these regions, it should not be confused with the alcoholic beverage known as cider in most parts of the world, called hard cider (or simply cider) in North America.
And a good article excerpt below ! From Discuss.org / History of Spirits in America (link not active anymore, hence unfortunately not a proper quote...)
The still-popular Laird’s Applejack can trace its roots to Scotsman William Laird, most probably a whisky distiller, and most definitely from the Highlands of Scotland. Laird settled in Monmouth County, New Jersey, in 1698 and set about applying his knowledge of distillation to apples rather than barley malt. Interestingly enough, cider-makers who didn’t possess a still would, during the winter months, leave cider outside to freeze. The following morning they discarded the frozen portion, leaving them with very strong cider--the alcohol content was concentrated in the liquid that didn’t, or couldn’t, freeze. Since the distillation of beverage alcohol is, in simple terms, the separation of alcohol from water, they were actually performing a form of distillation by freezing instead of heating.