I have been learning Jon's song The Mary because I love it so much. But even as a native New Yorker I find one phrase confusing, and no amount of googling so far has cleared it up. The phrase, "From the Congo to the kills," is what I'm stuck on. I get the Dutch word "kills" which refers to bodies of water, and several cities with that word in their names. But am I missing something? I've never heard of anyplace in NY named or nicknamed "the Congo."

Thanks in advance for any light anyone can shed on this.   

Joanne