[czinck]

Rhoticity is the big one I know. Parts of Britain started dropping the R before 1776, but it became more widespread after that. The US port cities (most notably Boston, but it was also a class difference) had enough contact with Britain that they dropped the R too, whereas the rest of the US kept it.

https://en.wikipedia.org/wiki/Rhoticity_in_English

[JetSetWilly]

I don't think anyone would consider rhoticity as especially American considering several dialects across the UK, ireland & canada are rhotic. It is just another way in which english varies globally.

[czinck]

True, and I didn't mean to imply it was. I was just thinking of things Americans say because of the British that the British no longer do, wasn't thinking America-exclusive things.