The Danish-American journalistJacob Riisvisited the slums of New York City to highlight the squalor in which the “other half” lived. He used flash photography (a new innovation), tables of statistics, and personal stories to vividly depict the city’s various neighborhoods and ethnic groups. But the book isn’t merely a factual documentary—it’s also a moralistic appraisal of greedy landlords, the abundance of cheap beer dives and saloons, the low character of...