is "In the first place" idiom specific only for american english?

No, we use it in Australian English too. There are lots of expressions which sound ‘American’ to us but this isn’t one of them. I think we’d be super interested in a list of these idioms that your teacher picked out!

No, it's a very common phrase in the UK. Unlike other idioms (such as "in the right ballpark"), I do not associate it with America.

sounds like your teacher is a poser

Very common in Britain. I would say that you would phrase it "You should have told me *that* in the first place!" Possibly the lack of 'that' makes it seem more American in style? Sometimes that's enough. e.g. I couldn't care less = British English I could care less = American English (like, how *much* less could Americans care, that's what we Brits always want to know! :D )

No that’s ridiculous, your teacher is wrong.

It's from the early to mid 16th century, so around the same time as the earliest British settlements in North America. Unless there's evidence otherwise, I'd assume it is used in both main branches of English. Even as a native speaker, I'd be careful of dismissing things as Americanisms. Yes, there's the annoyance of the kids picking up the current American slang online, but we do share a language and words and phrases do shift across different dialects. What were seen as Americanisms, decades ago, may be entirely normal now. I'm just hoping that Bluey will be our revenge!!!

It’s very common in England. Is your teacher actually English, or is she just teaching English?

Yeah, your teacher's wrong. Tell her the internet said so.

Your teacher is an idiot if they correct your "Americanisms" anyway. A good teacher should point them out to you when you use them so you are aware of what you do, but they should never discourage you from using them.

For the record, I'm a British native speaker of English and it sounds perfectly British to me. There are plenty of Americanisms making their way into British English, but this isn't one of them. What did she suggest that you should have said instead to make it sound more British?

I've never heard that expression referred to as uniquely American in any way. I've consumed a lot of media discussing different varieties of English and watched a good bit of British TV. That idiom/phrase just seems to be a part of English in general, not regionally specific.

No. It's used in both American and British English. The phrase means "originally" or "at the beginning." For example, you might say, "I didn't want to go to the party in the first place." Your teacher may have been mistaken, or they may have been thinking of a different idiom.

we definitely say that in the uk i don’t know why the teacher would call it an americanism - i’ve often said “why didn’t you say that in the first place?!”

I think it's a common phrase in English no matter where you are, it's not a uniquely American phrase

Not at all. And I don't think I would call it an idiom either. I'd certainly argue that it's a necessary phrase to learn

This source says it's first use was 1639 https://www.phrases.org.uk/bulletin_board/43/messages/317.html

Is your teacher English? This is not an idiom, but a prepositional phrase. Synonyms would be : initially, firstly

Maybe there's an argument it's too casual for academic writing, but it's certainly common. I've heard non-US English speakers use it quite a bit.

Apparently the OED has the first cited use as 1639, and it appears regularly in literature after that. So not specific to any particular variety of English. Some sources claim that it refers to a mnemonic for remembering things. Possibly the "Memory Palace" or a simplified version thereof.

I'm pretty sure that the phrase pre-dates the United States.

your teacher is a dumbass

"In the first place" is certainly not an Americanism *per se*. What I cannot vouch for is its use in formal settings. In the UK, it's not the most appropriate phrase to use in a proper, grown-up essay. It's slightly too informal and simplistic for academia, to my ears/eyes. It's a way of listing things in a rough order of priority which does not state the terms of the hierarchy. In fact, it's often (though not always) better to leave the most significant item for consideration until the end. My suspicion is "Americanism" was a somewhat inattentive shorthand for "colloquial". I don't think you'll find it favoured much in academic English anywhere. (But I stand to be corrected by the word stats people!)

It's used in Australia often , therefore it would have a British origin.... because you know , English came from England. Tell your teacher the internet thinks they're a fuckhead

Not unique to US/American English. However, that doesn't mean it belongs in an academic essay. There are a lot of phrases (especially idiomatic expressions) that we use in daily speech that should be avoided when writing an essay. Personally, I'd say 'in the first place' is borderline. Some teachers will be fine with it, some won't. It's a matter of formality more than anything.

No, to be proper British English eliminate the entire sentence inset a scoff and an eye roll. Serious answer, English, like all languages, are incredibly regional. You need to use -isms to sound native.

I'm British and I would not call that American, perhaps its used more frequently in America but its not America specific

No, I've heard it all my life in Australia

While we're here, it has two different meanings... 1. Like you used it, meaning something should/shouldn't have happened. 2. To start a sequence of reasons. E.g.  "Why wont you go out with me?" - "In the first place, I'm married. In the second place, you stink!"

no

I’m from Britain and it’s often used here, I wouldn’t call it an Americanism.

I’m Canadian and it doesn’t sound blatantly North American but we’ll see what the Brits say

"In the first place" feels more British than US to me as a Brit.

It's common in British English. The OED lists the first known appearance as 1639, so it does not look to be an Americanism that later became popular elsewhere either. I think it's standard English everywhere.