How the Other Half Lives is an influential 1890 photojournalistic book by Jacob Riis that documents the harsh living conditions in New York City slums during the 1880s. Riis used both words and pioneering photography to expose the squalor and overcrowding in tenement housing, highlighting the poverty, child labor, crime, and poor sanitation faced by the urban poor

. Riis argued that the tenement system was a failure caused by greed and neglect from wealthier classes, and that the poor conditions bred social problems such as crime and disease. He also noted the ethnic diversity of the slums, though his descriptions sometimes reflected the prejudices of his time. Despite this, he maintained that poverty was largely a product of environmental conditions rather than inherent traits

. The book concludes with Riis proposing practical reforms to improve housing and living conditions, asserting that the upper classes had both a moral and financial incentive to help solve the problems of the poor

. His work helped spur public awareness and reform efforts around housing and urban poverty in America. In summary, How the Other Half Lives is a landmark exposé that revealed the grim realities of life for the urban poor in late 19th-century New York, combining journalism and photography to advocate for social reform