Whether you’re writing about current politics or past outrages, understanding the difference between historic and historical can mean the difference between “this happened” and “THIS HAPPENED!!!”
Historical is the more commonly used word because arguably every event is historical. That is, it “relates to or occurs in history.” Just how much time must pass before something can legitimately be described as historical is more or less a personal choice. It might refer to when I burned the popcorn last Tuesday, or it might refer to last night, when I . . . burned the popcorn. Either way, historically, I have a problem with popcorn.
Something is historic if it has some special importance or significance. Like historical, there’s a lot of personal leeway as to what qualifies as historic. For example, my purchase of the foolproof Air-Master 3000 Popcorn Popper with automatic butterer and optional salt dispersal unit might not be a historic event for anyone else, but it would be a historic purchase for me.
How to Remember
As I mentioned before, practically anything can be said to be historical, and therein lies the basis of a mnemonic. All things can be historical; historic, the smaller of the two words, applies to a smaller set of events, things, and places.
A vs. An
Historically, there has been some controversy over which indefinite article, a or an, to use with these words. The details of that controversy are alternately fascinating and tedious, but authorities these days generally apply the same “rule” to these words that they apply to every other word.
It’s all about pronunciation: If the word begins with a vowel sound, use an; if it begins with a consonant sound — and that includes an aspirated H — use a. This is true in both American English and British English, and it’s really nothing new. Even H.W. Fowler, back in 1926, recommended a historic and a historical.