"An" before "Historic", Historian, History, etc is just plain wrong
It is only right (pick one or more of the following) if you speak:
1) without aspirating "H"
2) French
3) Cockney
4) with a pretentious attitude
5) while ignoring the basic rules for use of indefinite articles
6) really, really olde English
7) wrongly thinking the "H" is silent (like 'p' in 'swimming')
8) incorrectly
9) like you're trying too hard to be a misguided broadcaster
10)as if you want to sound posh
Canada Post got it right......this time.
That's A HISTORIC event!
Now, if we could only get people to stop saying Yooge, Yooman and Yooston (Texas).