The Great Railroad Strike of 1877, sometimes referred to as the Great Upheaval, began on July 14 in Martinsburg, West Virginia, after the Baltimore and Ohio Railroad (B&O) cut wages for the third time in a year. This strike finally ended some 69 days later, after it was put down by unofficial militias, the National Guard, and federal troops. Because of economic problems and pressure on wages by the railroads, workers in numerous other cities, in New York, Pennsylvania and Maryland, into Illinois and Missouri, also went out on strike. An estimated 100 people were killed in the unrest across the country. In Martinsburg, Pittsburgh, Philadelphia and other cities, workers burned down and destroyed both physical facilities and the rolling stock of the railroads—engines and railroad cars. Local populations feared that workers were rising in revolution such as the Paris Commune of 1871.

At the time, the workers were not represented by trade unions. The city and state governments were aided by unofficial militias, the National Guard, federal troops and private militias organized by the railroads, who all fought against the workers. Disruption was widespread and at its height, the strikes were supported by about 100,000 workers. With the intervention of federal troops in several locations, most of the strikes were suppressed by early August. Labor continued to work to organize into unions to work for better wages and conditions. Fearing the social disruption, many cities built armories to support their local National Guard units; these defensive buildings still stand as symbols of the effort to suppress the labor unrest of this period.

With public attention on workers' wages and conditions, the B&O in 1880 founded an Employee Relief Association to provide death benefits and some health care. In 1884, it established a worker pension plan. Other improvements generally had to await further economic growth and associated wage increases.