Answer:
The Progressive Era
The Progressive Era was a period of social activism and political reform in the United States that flourished from the 1890s to the 1920s.
Explanation:
The three primary reasons are <em>the requirements for Confederate states to reenter the Union; overseeing the rebuilding of a Southern economic infrastructure; the fate of millions of freed slaves.</em> These were the main issues and hot topics of American Civil War during that time.
