Final answer:
The Progressive Era began in response to rapid industrialization, immigration, and urbanization in the late 1800s. Progressives aimed to address social inequality and promote social justice through government regulations and grassroots movements.
Step-by-step explanation:
The Progressive Era began in response to several challenges faced by the United States in the late 1800s, including rapid industrialization, immigration, and urbanization. These factors created social inequality and led to issues such as corruption, poor working conditions, and anti-Black violence. The reformers of the Progressive Era, known as Progressives, aimed to address these problems and promote social justice through government regulations and grassroots movements.