Identify three characteristics of American Urbanization

     Urbanization in the United States took place in waves; however, the late nineteenth and early twentieth century represent the height of urbanization due to a drastic rise in industrialization. Three characteristics of urbanization in the United States can be identified:
Migration of the rural population into urban centers, which in turn led to a significant drop in the rural population. People migrated to cities to work in factories.
The emergence of tenement housing and slums. Tenement houses were mostly occupied by impoverished families (workers, immigrants). These buildings were infamous for unsanitary conditions and for being unsafe (e.g., not enough fire exits). The existence of tenement housing also speaks to the emergence of a poor working class.   
Expansion of transportation infrastructure in cities. To deal with the large amount of people living and traveling within the city, municipalities built mass transit (subway, trolleys, buses, etc.).
http://www.loc.gov/teachers/classroommaterials/presentationsandactivities/presentations/timeline/riseind/city/