Urban Reformer Jacob Riis was a Danish-American journalist, social reformer, and photographer. He is best known for his work documenting the plight of the poor in New York City in the late 19th century. Riis used his photographs to illustrate the problems of poverty and overcrowding in the city, and he wrote books and articles advocating for social reform. He is credited with helping to bring about significant changes in housing and labor laws in the city.