Since most speakers pronounce the h, it takes "a" not "an".
Contrast to "an hour", where the h is silent.
The British pronounce it as "istory," so they use "an" before.
"The British" aren't monolithic and neither are our approaches to this.
I certainly don't say "it is an historic day" or "staying at an hotel" with the soft H, because to me, in the 21st century, it's an upper class affectation (I am from a middle class background and from the commuter belt 30 miles south of London).
I moved to a slightly posher place and I know people who do say "an historic day" (soft H) still but it's largely out of habit/age/schooling.
The BBC have stopped doing this, as a rule. The monarchy have moderated this aspect of their speech too — I am sure I remember the younger Prince Charles say "an historic day" with the soft H, but I am fairly sure he would now say "a historic day" with the hard H; he has been trying to progressively moderate his RP accent for the last 25 years or so.
ETA: clarification in reply to reply
Having said that, there are two constituencies that do it, I guess:
- Those who do it out of upper class background or affectation: using the French soft H that survives in the American pronunciation of 'herbs' is a class signifier.
- And those who do it out of broader dropped-H slackness; it's not out of the question that someone would say "it's an 'istoric day" run together, in a variety of regional and rural accents.
So if you meant the latter, then, yes! Probably more people do it as a result of dropping H more generally than out of upper class identification.
But in the middle of those two, most of us, I think, use the hard H, and certainly "BBC English" has moved in that direction.
For me, on this one, if there's an "an", it pushes me to not pronounce the "h" in the next word, even though I consider it silly to pronounce "historical" that way.
"A his-toric day"
"An his-toric day"
Both seem to work correctly with American pronunciation.
Journalists and films seem to use "an historic" with an American accent, which breaks the rule but still feels correct.
For most words the indefinite article is clear. This one feels weird.
No it doesn't. If I pronounce the "h", then using "an" sounds weird. If I don't, then "a" sounds weird.
> Journalists and films seem to use "an historic" with an American accent
Curious if you have a link to a video of this, I can't imagine it sounding correct.
> Rachel Maddow "an historic day"
For example:
"An historic" is certainly used in the US, but it's wrong in all contexts.