I found this to be somewhat interesting, given the early date:
It's a brief mention in the February 7, 1844 edition of the Elyria, Ohio, Lorain Republican of an equally brief attempt by a member of the Ohio legislature to levy a tax on banjos and harmonicas in addition to pianos.
That was almost exactly a year after the Virginia Minstrels shows at the Bowery Theater, which I tend to think of as the catalyst for the banjo entering the national popular culture consciousness (even though I do realize banjos were being used onstage in the decade or two before that). I know the minstrel/banjo "craze" spread very quickly, but I guess I was still surprised to see that banjos were evidently common enough a year later for someone to propose they be taxed along with an instrument such as the piano.
(Thanks to Michael Murphy for finding that article, which he posted on BanjoHangout.)