Jacob August Riis (May 3, 1849 - May 26, 1914), was a Danish American social reformer, muckraking journalist and photographer. He is known for his dedication to using his photographic and journalistic talents to help the impoverished in New York City, which was the subject of most of his prolific writings and photography. He helped with the implementation of "model tenements" in New York with the help of humanitarian Lawrence Veiller. As one of the most prominent exponents of the newly practicable flash, he is considered a pioneer in photography.