This 3rd grade unit introduces the history of industrialization in the United States in the late 19th century. The development of mechanization and assembly line processes, reliance on unskilled labor, and geographic concentration of certain businesses shifted the U.S. economy from individual craftsman-based production to mass production. Students examine elements of industrialization, including invention, mechanization, and use of unskilled labor, and construct an inventory of industrialization's positive effects and its unhealthy consequences.