Okay everyone who says ‘an historic’, you’re driving me nuts.  You say ‘an’ before a vowel or a vowel sound.  You say ‘a’ before a consonant or consonant sound.  H is a consonant and in the word historic makes a consonant sound; therefore, the event you’re talking about is a historic event, not an historic one.  If the word starts with an H and has a vowel sound, then you can say an.  Here is an example of each:

Barack Obama being elected president was a historic event.

I hope he is an honest man.

Got it?  Now knock off the “an historic” bullshit, you sound like an idiot.