any musical instuments that have been invented in the United states would be great. Thank you.

Well, the sousaphone was presumably invented by or named after John Philip Sousa. I imagine it’s American.

I imagine we might also be responsible for one or another of the various banjos, and a funny guitar with a metal sounding board called a dobro. There’s also the autoharp.

We’re probably also guilty of things like the banjolele and similar combination instruments.