Both "a historical" and "an historical" are used, but the article "a" is far more common, particularly in American English.

Most American English speakers pronounce “historic” with an audible “h”, so they generally say and write “a historic”. Some British English speakers, by contrast, pronounce “historic” without the “h”.

It's a useless. The adjective useless begins with a consonant sound, a "you" sound, so it takes the indefinite article "a".

hoose the article ("a" or "an") that best suits your own pronunciation. Remember, we use “a” with words that begin with a consonant sound.

The British say a herbivore since the "h" is silent. An American English speaker, however, typically chooses the article (a/an) that best suits his or her own pronunciation.

The noun herbicide is more often pronounced with a sounded "h"; thus, "a herbicide" is more common. However, some American English speakers don't pronounce the "h" and say "an herbicide". Remember, the rule for using a or an is based

Most British English speakers say a herbaceous since the “h” is typically silent in British English. Americans, however, choose the article (a/an) that best suits their own pronunciation.

When speaking American English, we usually say an herbal because the initial letter of this word, the “h”, is silent. The British, however, commonly use the article "a" since the “h” is sounded in British English.

In American English, it’s an herb since the “h” is silent. In Britain, by contrast, the “h” is typically sounded, so they say “a herb”.