Which one is it?
To me, historic refers to an event or location or other item that has made a name for itself in history while historical is a term that refers to a general quality that recalls an earlier era. The battle of the Alamo was historic, but the re-enactments of said battle are historical. Likewise, the Alamo chapel is a historic structure, but tourists come to San Antonio in part to enjoy the city's historical heritage.
I bring this up because this morning a Today show anchor referred to the blizzard that's been sweeping across the northern United States as a "historical Christmas storm". That usage mildly bothered me. If the storm goes down in the record books as particularly severe or long-lived, then it seems to me that that the storm is historic. You might refer to "historical" Christmas weather, but particular storms are "historic".
But perhaps I'm making too much of it. In fact, in my job, we sometimes have to deal with old structures or locations, and in my company's own paperwork I have noticed that "historic" and "historical" are used interchangeably. I seem to be the only one that even notices there are problems with the usage sometimes, so maybe I'm also the only one with this little linguistic hang-up.
What about you? Have you ever considered the differences between "historic" and "historical"?