Riis, Jacob A. - Battle Alley, Hauptquartier der Whyo – Bande (Zeno Fotografie)

Jacob August Riis (1849–1914) was a Danish-American social reformer, journalist, and social documentary photographer. He contributed significantly to the cause of urban reform in America at the turn of the twentieth century. Riis exposed the crises in housing, education, and poverty at the height of European immigration to New York City in the late nineteenth century. Riis and this circle of municipal citizen-reformers, which included social welfare activists Josephine Shaw Lowell and Lillian Wald, worked to gather statistical evidence and raise public awareness. They advocated for new housing designs to ease crowding and improve fire safety, sanitation, and access to air and light. Riis was among the first in the United States to use photographic images as instruments for social change; he was also among the first to use flash powder to photograph interior views and his book How the Other Half Lives was one of the earliest to employ halftone reproduction successfully.

Jacob Riis (1849—1914) was a Danish-born American muckraker journalist, photographer, and social reformer. He is known for his dedication to using his photojournalistic talents to help the less fortunate in New York City, which was the subject of most of his prolific writings and photographic essays. As one of the first photographers to use flash, which allowed him to document the reality of people's situations in the dark slum areas at night, he is considered a pioneer in photography.