The billboard stands rather unremarkably in a field of tall grass, a few hundred yards beyond the high barbed-wire fence, past the NO TRESPASSING signs and across some towering cranes and rusted tracks. It reads: WELCOME TO FLINT, PLEASE BE CAREFUL. It is an uninspired sign featuring a cartoon CSX conductor--one of those corporate image-enhancing niceties that until a few weeks ago blurred into the desolate industrial landscape like so many slabs of sheet metal. For whom the sign's message is intended has always been unclear; CSX trains only carry freight, and it's too far away for motorists traveling the nearby...

