The document summarizes key events and developments during the Progressive Era from the 1870s to 1920. It discusses how muckrakers raised public concerns through exposés like Upton Sinclair's The Jungle, leading to new laws regulating the food and drug industries. Industrialization led to large factories in northern cities, attracting many immigrant workers who faced overcrowding and unsafe conditions. Jacob Riis documented these problems in How the Other Half Lives. The US engaged in imperialism and acquired colonies in places like Cuba, the Philippines, and Guam. Isolationism after WWI hurt European economies and contributed to the rise of dictators.