"A historic" or "an historic"?
Summary
Both usages are sufficiently common to be considered correct in modern English.
You probably know the grammar rule that says you use an before vowel sounds (e.g. an accident, an item, an hour) and a otherwise; e.g. a book, a report, a hotel.
Following this rule, we would say "a historic", not "an historic".
Words of three or more syllables that start with h are treated differently by some speakers, though. For example, which of these pairs of sentences sounds correct to you?
- It is a historic occasion.
- It is an historic occasion.
- We can't agree on a hypothesis.
- We can't agree on an hypothesis.
A quick bit of Googling reveals that — as of March 2008 — the phrase "a historic" is used on 5.1 million pages (68%), and "an historic" on 2.34 million pages (32%).
There is a clear preference here in favour of "a historic". Even so, roughly one-third of the usage is for the other form. This supports the view that which form you use is little more than a personal preference.
Both usages are sufficiently common to be considered correct in modern English.
