Which period of time in American history is commonly referred to as the Progressive Era?

The Progressive Era in American history is identified as the period from 1890 to 1920. This was a time of widespread social and political reform aimed at addressing issues caused by industrialization, urbanization, and corruption in government. Reformers sought to improve working conditions, promote social welfare, expand democracy, and combat monopolies and corruption. This era saw significant legislation and constitutional amendments, including women's suffrage and reforms in labor laws.

Other options reflect different historical contexts and developments that do not align with the primary focus of the Progressive Era. The period from 1920 to 1929 encompasses the Roaring Twenties, a time characterized by economic prosperity and cultural change, while the periods from 1945 to 1960 and from 1960 to 1972 involve post-World War II changes, civil rights movements, and other significant events that are distinct from the aims and accomplishments of the Progressive Era.