Which significant labor strike in July 1877 involved railroad workers and led to federal troops being sent to restore order?

The Great Railroad Strike of 1877 is recognized as a pivotal moment in U.S. labor history due to its scale and significance. This strike was initiated by railroad workers protesting wage cuts and deteriorating working conditions in the aftermath of the Panic of 1873. As the strike escalated, it spread across multiple states and led to violent clashes between strikers and law enforcement, particularly in key cities like Baltimore and Pittsburgh.

The federal government's response to this crisis was notable; President Rutherford B. Hayes ordered federal troops to intervene and suppress the strike in order to restore order and ensure the movement of trains and freight. This marked one of the first instances of federal military intervention in a labor dispute, reflecting the tensions between labor and government authority during this period. The strike highlighted the struggles faced by workers and the conflicts inherent in the rapidly industrializing American economy.

The other choices listed, such as the Pittsburgh Strike of 1882, the Pullman Strike of 1894, and strikes led by the United Mine Workers, were significant in their own right but did not occur in July 1877 or involve the same scale of federal military response as seen in the Great Railroad Strike of 1877.