Photographer. Also a social reformer. A pioneer of documentary photography, he used his craft to rouse the public about societal problems, especially conditions among the urban poor. Although his intentions were purely factual, his deftly composed and skillfully lighted images are as powerful as they are informative. Riis's well-known How the Other Half Lives: Studies Among the Tenements (1890), illustrated with halftones and line engravings taken from his photographs, inspired new building codes and measures to clean up slums. Born in Ribe, Denmark, and trained as a carpenter in Copenhagen, Riis arrived in the United States in 1870. While working as a journalist in New York, he became outraged at the cycle of poverty, crime, and despair that he witnessed in lower-class neighborhoods. The invention of the magnesium flash, which for the first time made short exposures possible in low light, spurred his determination to supplement his writing with visual evidence. At first he worked with amateur volunteers, but in 1888 he began taking his own photographs. Although his work as a photographer was limited to the next ten years, his impact was not. Among the first photographers to confront unpleasant realities without relying on picturesque sentimentalities, he produced unflinching records that advanced the course of documentary photography. Riis's most striking and original works are the photographs he took of people in their decrepit homes or back-alley hangouts. “Home of the Italian Rag Picker, Jersey Street” (c. 1888–89), a particularly stirring image, captures in the harsh light of Riis's flash a careworn woman holding an infant while seated among her rag bags within a cramped interior. Washtubs, a dustpan, a hat hung neatly on the wall, and a clear space in the room's center suggest her resistance to chaos. As is usual among his portraits of the downtrodden, Riis gives pictorial importance to the immediate environment, reinforcing his reformist message that the problems of the poor are embedded in their surroundings. Riis published more than a dozen books, including several promoting reform and a biography of his ally President Theodore Roosevelt (1903). The title of Riis's autobiography, The Making of an American (1901), hints at the patriotic and optimistic motivations for his crusade. He died in the central Massachusetts town of Barre, where he had moved only the previous year.