What violent event galvanized public opinion in favor of labor's position and led to a progressive era of reform?

The Ludlow Massacre is the event that significantly galvanized public opinion in favor of labor's position and led to a progressive era of reform. This tragic incident occurred in 1914 when striking coal miners and their families were violently attacked by the Colorado National Guard while they were living in a tent colony in Ludlow, Colorado. The attack resulted in the deaths of numerous individuals, including women and children, and exposed the brutal conditions faced by laborers.

The incident drew national attention and outrage, highlighting the extreme measures that employers and the government were willing to take against organized labor and the plight of workers. The public outcry following the Ludlow Massacre played a critical role in shifting perceptions about labor rights and prompted a greater demand for labor reform, including improvements in working conditions, labor laws, and union recognition.

This event and its aftermath contributed to the broader Progressive Era, during which social justice and workers' rights became central issues and led to significant legislative changes aimed at addressing the inequalities faced by workers.