Final answer:
According to Jacob Riis, the conditions in the slums were overcrowded, rundown, and unsanitary. These poor living conditions led to the spread of diseases. Riis's work helped raise awareness and bring about reforms in tenements in New York City.
Step-by-step explanation:
The conditions in the slums, as described by Jacob Riis, were overcrowded, rundown, dirty, and unsanitary. Many families had to live in cramped apartments, with one or two dark closets used as bedrooms and a small living room. The buildings themselves were crammed together, lacking fire protection and indoor plumbing. These poor living conditions led to the spread of diseases like tuberculosis and pneumonia.
Riis's photographs of the slums exposed the living conditions to the public and helped generate support for change. He advocated for improving tenements and building new ones to address the overcrowding and lack of sanitation. Riis's work, along with other reporters and activists, contributed to the passage of laws to improve tenements in New York City.