The rapid growth of cities in the late 19th century led to many urban problems. As factories grew and immigrants arrived, the urban population in the United States swelled from 10 million to 54 million between 1870 and 1920. This mass migration to cities from rural areas and other countries created issues with housing shortages, inadequate transportation and infrastructure, and poor public health and sanitation standards due to overcrowding and lack of services. Cities struggled to provide sufficient housing, transportation, water, waste removal, healthcare, and prevent the spread of disease in the fast-growing urban areas.