The American Industrial Revolution of the mid-19th century created unprecedented growth in the urbanisation of U.S. cities. By the beginning of the 20th century, more Americans lived in cities than in rural communities for the first time in the nation's history. Much of the growth can be attributed to working class families who moved to the city in search of jobs, and immigrants in search of a better life. Life for the working class during the early 20th century was often difficult due to harsh working conditions and urban overcrowding.
In the rapidly developing east, such cities as Youngstown, Pittsburgh and Detroit were built around industry. Steel mills, textile and automobiles factories offered unskilled labourers a chance to earn a modest income, but at high cost to their health and well being. Life would revolve around the factory, with many labours forced to work 12 hour shifts, six days a week. Conditions in factories were less than ideal, leading to dangerous work environments that led to a high number of worker fatalities. A fire in 1911 in New York City's Triangle Shirtwaist factory killed 146 workers, mostly young women, and the Bureau of Labor Statistics documented 23,000 work-related deaths nationally in 1913 alone.
The rapid growth of cities caused a massive overpopulation in urban areas. Tenement housing was often dark and poorly ventilated, where two or three families would share one apartment. Such cramped conditions created public health hazards, and a rise in the spread of infectious disease. By the beginning of the 20th century, municipal governments were passing anti-tenement and public safety legislation in an attempt to promote better living conditions. As cars became more common and public transportation more reliable, families who could afford it were able to move to less crowded suburban areas.
The 1900 U.S. census counted 1.75 million children aged 10 to 15 who were gainfully employed as workers. Child labourers accounted for 6 per cent of the U.S. workforce during the early 20th century. Many families depended on the income generated by their children in order to survive. Children were not spared the long hours that their parents were forced to work, and often did so making much less than their mothers and fathers. Children were routinely used to fix broken machinery, because their small hands and tiny frames allowed them to squeeze into areas adults could not. While some states had laws against child labour, the The National Child Labor Committee only succeeded in helping pass federal laws that regulated child labour in 1938.
The massive overcrowding of cities gave rise to such large public parks as Central Park in New York City and Golden Gate Park in San Francisco. An important part of public planning, parks gave families the chance to escape the blight of their tenement housing for fresh air and a field of green grass. The early 20th century also saw baseball become the national pastime of America. Fenway Park, Wrigley Field and Yankees Stadium were all built in the early 1900s to accommodate the large crowds that flocked to stadiums to enjoy an afternoon of baseball.