The American city went through various transformations in the 1950s. Technological, economic, and demographic changes resulted in a new national urban and suburban system. Both Chicago and Brooklyn played crucial roles in the urban system in place before 1920. As the post-depression and post-World War Two era dawned both Chicago and Brooklyn saw their relative positions in the social and economic life of the United States shift. The paper will look at these changes and investigate their impact on these two important American cities.