Early Documentary Photography – The Metropolitan Museum of Art https://www.metmuseum.org/essays/early-documentary-photography
Photographers used its growing influence to expose society’s evils, which the prosperous, self-indulgent Belle Époque chose to ignore: the degrading conditions of workers in big-city slums, the barbarism of child labor, the terrorism of lynching, the devastation of war.
building codes and slumlord-tenant relations, the book continues to serve as a model