The great railroad strikes of the summer of 1877, as the young labor leader Samuel Gompers noted, sounded an alarm that heralded a new era of conflict and division in the nation. Issues of slavery and emancipation had preoccupied Americans’ minds during the previous decades, as the bloody Civil War led to Reconstruction—a time when the freedpeople in the post–Civil War South not only gained their freedom but also secured U.S. citizenship, the right to vote and hold elective office, access to education, and some modest measure of economic and religious independence. However, in the early months of 1877, the newly installed administration of Republican president Rutherford B. Hayes agreed to withdraw the few remaining federal troops that were keeping order in the southern states in exchange for Democratic party support for Hayes’s contested election. As Reconstruction crumbled, industrial capitalism flourished, and the nation’s working men and women fought to find a place for themselves amid the extraordinary economic, political, and social changes of the next four decades.

The United States became the world’s most powerful industrial nation during the years between the end of Reconstruction and the beginning of World War I, boasting massive manufacturing enterprises and unprecedented productivity. In this same period, the nation launched a war with Spain that resulted in U.S. domination of Puerto Rico, the Philippines, Cuba, and Hawaii. The face of America also changed, as millions of immigrants from Europe, Asia, and Latin America poured into the United States after 1900, feeding industrial capitalism’s seemingly insatiable appetite for new workers. Urban America took modern form and shape as the populations of New York and Chicago swelled beyond a million residents each and contemporary transportation, sanitation, and safety systems came into being. New consumer products, new means of mass distribution, and new forms of recreation reshaped everyday life in the city and the countryside.

U.S. capitalism enabled the growth of economic monopoly, unimaginable individual wealth, and unbridled political power. It also made many Americans—as well as the millions of other individuals who lived and worked under U.S. control in the Caribbean, Latin America, Asia, and the islands in the Pacific Ocean—dependent on wages or on market relations. Americans were sharply divided on the meaning of the changes in their nation. On one side stood industrial capitalists and their political and intellectual supporters. They justified capitalists' newly won wealth and power with an ideology that celebrated acquisitive individualism, free markets, and the “survival of the fittest.” On the other side stood the working men and women whose labor powered the system—African Americans, native-born white Americans, and European, Latin American, Caribbean, and Asian immigrants. They embraced the ideal of collectivity and the power of mutual rather than individual action to blunt the devastating impact of industrial capitalism on their work and family life and their communities. Of course, many Americans—small business owners, machine politicians, white-collar workers—did not entirely agree with either position, siding with industrial capitalists in some circumstances and with working people in others. And working people themselves were often divided along lines of race, gender, ethnicity, religion, and region.

As the dizzying growth of industrial capitalism transformed people and communities, cultures of collectivity arose. From those bases, working people launched a series of violent class wars that were unprecedented in the nation’s history. They carved the names and dates of individual battles into the public consciousness: Haymarket (1886), Homestead and Coeur D’Alene (1892), Pullman (1894), Lawrence (1912), Paterson (1913), and Ludlow (1914). Radical ideologies embraced by workers craving change, including populism, feminism, anarchism, and socialism, animated many of these conflicts. By 1900, many of the most fundamental challenges to industrial capitalism in the Gilded Age—the Knights of Labor and the Populists, in particular—had been beaten back.

At the same time, this heady brew of labor struggle, political unrest, and a spate of tragic factory fires and coal mine explosions fostered a belief, shared by workers, middle-class professionals, and even some business leaders, that someone needed to take action against the problems caused by capitalist excesses. This conviction drove a series of reform movements, often spearheaded by women, which collectively came to be known as progressivism. Progressivism articulated a modern notion that government should play a central role in regulating the nation’s social, economic, and political ills. Reformers successfully addressed some of the issues facing the nation: child labor, factory safety, tainted food and drugs, political corruption, and unchecked economic monopoly. Women pushed harder than ever for their right to vote. But the progressive movement did little for African Americans, who saw only regression from the gains they had won during Reconstruction.

As war loomed over Europe, the particular concerns that gave rise to progressivism would increasingly take a back seat to concern over the spreading international crisis. Nonetheless, progressive reform inaugurated a new era in U.S. politics, one in which the federal government took some small steps toward its now familiar role as guarantor of economic stability and the basic safety and health of its citizens.