The Progressive Movement was the reform movement that ran, generally, from 1890-1920, during which social reformers made up mainly of the middle class intellectuals who sought to address the issues of industrialization that were literally transforming America into an economic super-power. These issues were new and some not expected and, in general, fall under social, economic and political categories. The Progressives believed, and frankly correctly, that the individual was being consumed by the capitalist nature of society.
I teach abolitionism as an early reform period. As we know, abolitionists saw the moral wrong of slavery, though by no means were they necessarily for equality with regard to Civil Rights, that would take until the 1960s.
By the early 1900s “Muckrakers,” as Roosevelt called them were based on a fictional character in John Bunyan’s Pilgrim’s Progress, were addressing important issues of the time: child labor, women suffrage, immigration, political corruption, health and sanitation, and much more. Progressives believed that government had to take charge and regulate and at times mandate in order to right some of these wrongs. It should be noted, however, that racism and the plight of blacks and Indians was of course not addressed.
However, is it relevant to also include the following:
Lincoln Steffens was a communist and after a meeting Vladimir Lenin proclaimed: “I have seen the future, and it works.” Steffens developed an enthusiasm for Communism after visiting Lenin.
Upton Sinclair was a socialist and even ran for office as such.
Margaret Sanger launched the monthly periodical The Birth Control Review and Birth Control News and contributed articles on health to the Socialist Party paper, The Call.
John Dewey identified himself as a democratic socialist.
Robert LaFollette was clearly a socialist.