Jacob August Riis (1849–1914) was a Danish-American journalist, social reformer, and photographer whose influential work shed light on the dire conditions faced by the urban poor at the turn of the 20th century. Born in Ribe, Denmark, Riis immigrated to the United States in 1870, settling finally in New York City. Riis' seminal work, 'How the Other Half Lives' (1890), utilized photography to expose the squalid living conditions in New York City's tenements, effectively bringing the plight of the residents to the attention of the wider public and prompting social reform. His photographic approach was pioneering, employing flash powder to reveal the darkness in which his subjects lived, both literally and metaphorically. 'Children of the Tenements' (1903) followed in this tradition, further documenting the struggles of impoverished youth and echoing his advocacy for better living conditions. Abroad from his social-documentary literature, Riis was also noted for his narrative style, which combined stark factual reportage with emotional storytelling, so as to appeal to the conscience of his readers. Throughout his career, Riis' work significantly contributed to the Progressive Movement and left an indelible mark on journalism and social advocacy, influencing housing reforms and child labor laws. His time as police reporter for the New York Tribune provided him with firsthand experiences of the tenements, which informed his passionate crusade for change. Riis' legacy is multifaceted; he is remembered as an early American muckraker, a photographer of social conditions, and a compassionate voice for the marginalized in urban America.