[Herr-Berbunch]

The spelling of whisky, or whiskey, differs geographically. As a rule, American and Irish prefer ‘whiskey’ and the Scots, Canadians and the rest of the world’s single malt makers prefer ‘whisky’. This originated during the 19th century. For in around 1870, Scotch whisky was of very low quality, much of it being distilled poorly in Coffey stills. For exportation to America, the Irish distillers wanted to differentiate their product from the poorer Scotch whisky, thus they added the ‘e’ to mark the crucial distinction. Today, Scotch whisky has become one of the world’s greatest spirits, but the spelling still differs. On mass, Americans still spell their spirit with an ‘e’, though legally it is spelt ‘whisky’. A few distillers, Maker’s Mark and George Dickel for example, prefer the Scottish spelling, this is to be attributed to their Scottish ancestry.

http://www.masterofmalt.com/whisky-or-whiskey/