Final answer:
The period being referred to in the statement is the Post-World War II era, specifically the 1950s and 1960s, which saw a significant economic boom and improvements in the standard of living for the American middle class.
Step-by-step explanation:
The statement referring to the increasing prosperity of the American people and a period of economic growth and prosperity is describing the Post-World War II era, specifically the 1950s and 1960s. After World War II, the United States saw a tremendous economic boom. Unemployment rates plummeted as mass production, particularly of automobiles, drove up consumer demand. Cities expanded, and a majority of citizens began to reside in urban areas. The standard of living for many Americans rose, with the middle class expanding due to well-paying industrial jobs. Consumerism flourished as people used their wartime savings to buy new commodities such as cars, televisions, and household appliances. The era was marked by the blossoming of the American middle class, substantial industrial growth, and increased accessibility to higher education, which, for many, became a pathway to achieving middle- or upper-class status.