As cities grew rapidly in the late 19th century due to immigration and industrialization, overcrowding and unsanitary conditions became major problems. Lack of proper housing, transportation, water, sewage and waste removal led to the spread of disease. Jacob Riis' 1890 book "How The Other Half Lives" documented these terrible living conditions in New York City tenements through photographs and drawings, helping to spark reforms to improve urban planning, housing, and public services.