They seem to bounce and wobble from one side to the next. The drugged-out, half-alive skeletons of Kensington Avenue in Philadelphia make their way past erected tents and filthy sidewalks en route to their next fix. How Kensington Avenue, a poverty-stricken place in one of the most impoverished cities in the country, gets away with brazenly being the center of one of the largest open-air narcotics markets in the United States is frightening, bewildering, and telling. It's a race to the city morgue for many inhabitants of Kensington injecting themselves in broad daylight. And with so many new places like...