There were non-mass-produced harmonicas in the early 1830s. Hohner began its manufacture in the early 1850s and they came to America pretty soon after production began.

I think I read all this in a book called "Band in a Waistcoat Pocket" written by an Australian (whose name I always knew, but has just slipped my mind.) There might be a history in the American book. "Harmonicas, Harps, and Heavy Breathers" (again, I forget the Author's name)

Murray