Isn't there a Schuykill River around Philadelphia, too? Not that that there weren't Dutch in PA also, but the term isn't entirely NYC.

Yes, indeed there is, wofa. (pronounced Skoo-kill, BTW) And there's also the notorious Schuykill Expressway, more "affectionately" known as the Surekill Expressway.

And thanks to Helen for pegging that early...there's also the Arthur Kill between Perth Amboy, NJ, and Staten Island, and the Kill Van Kull [sp?] in the NYC region, too.