Between 1848 and 1860, societal changes created by immigration, industrialization, western expansion, and the growth of slavery led to repeated confrontations between political leaders as well as among ordinary Americans. Political compromises, such as the Compromise of 1850 and the Kansas-Nebraska Act, resolved the most bitter issues for a time. But it was not until the North defeated the South in the Civil War that the most volatile issue—slavery—was finally settled and the future development of the United States under industrial capitalism assured. The dramatic and bloody events surrounding the Civil War constituted a second American revolution, which formed the centerpiece of this era.

This second revolution resulted not only in emancipation but also in a fundamental expansion of legal guarantees of citizenship and political equality. In this way, it paralleled the first American Revolution when colonists gained both independence from Great Britain and the liberties guaranteed in the Bill of Rights. Still, like the first revolution, the Civil War and its aftermath demonstrated that differences of class, race, and sex still limited the practical implementation of constitutional claims for equality.

From the end of the Mexican American War in 1848 through the 1870s, women and men—including African Americans, Mexican Americans, Chinese and European immigrants, and native-born white Americans—continued to build the expanded territory that was America. They constructed towns and railroads, managed farms, and extracted minerals in the West; furthered industrial and commercial growth in the North; and contributed mightily to agricultural production in the South and Midwest. Members of the laboring classes also engaged in the era’s increasingly heated debates over immigration, westward expansion, and women’s rights, even as they banded together to advance social and political causes.  They joined both antislavery and antiabolitionist groups; formed unions and staged strikes; and participated in political rallies, electoral campaigns, and the founding of the Republican Party. Large numbers of working-class men eventually took up arms to further one cause or other—the defeat of Mexico, battles in Native territories, and Confederate independence or the salvation of the Union.

Although few Americans believed, even in the 1850s, that the struggle over slavery would erupt in a civil war, when war finally broke out in April 1861, nearly all Americans’ lives were affected in profound ways. The South seceded from the Union to maintain the system of racial slavery upon which the region’s very identity was based. Northern white people went to war, for the most part, not to free the enslaved African Americans, but to limit slavery’s expansion westward and to maintain the Union.  Still, during the South’s departure from the federal Congress, legislators from the free states reshaped western development by funding the transcontinental railroad and passing the Homestead Act. This legislation would gradually transform western society, further limiting the ability of Native Americans to maintain traditional lifeways. The war also transformed women’s lives.  As men were drawn into the military, their wives, sisters, and daughters took over jobs in fields and factories, managed businesses and plantations, entered new occupations as clerks and nurses, and formed organizations to aid soldiers and newly-freed people. 

Over time, the purpose of the war itself changed, especially for the Union. As the North faced unexpected military defeats and the unanticipated actions of enslaved people, more and more northerners embraced emancipation as a critical goal of the war. African Americans escaped from slavery in huge numbers. Many of them, along with northern free Black people, demanded the right to fight for the Union, and ultimately, nearly 200,000 African Americans served in the Union Army. They helped turn the tide in the war’s final two years and convinced northerners to fight for the end of slavery as well as the preservation of the Union.  

Neither side in this conflict was completely united. Clashes erupted within the South and the North over the war’s personal, economic, and political costs. In the North, however, a broad coalition—farmers, workers (including recent immigrants), businessmen, and politicians—emerged to support the Republican Party’s policy of massive military action against the South. This wartime coalition then formed the core of support for Republican policies toward the South after the war.

The Confederacy’s defeat raised as many questions as it answered. Slavery was now destroyed, but what kind of labor system would replace it? African Americans were now free, but what would they do with their new freedom? How would their former masters react? Who would lead the new South now? The policies of the period called Reconstruction attempted to answer these questions.

The freedpeople knew exactly how they wanted those questions answered. To them, emancipation meant the right to speak and act as free people, to reunite their families, and to end their automatic deference toward whites. And freed men and women acted decisively to guarantee these freedoms; their claims of individual rights quickly grew into collective demands for education, the ownership of land, and full political participation.

White southerners had a very different notion of what Reconstruction should mean. Former enslavers wanted a rapid return to stability and a continuation of their rule in spite of emancipation. Few of them could abide the freedpeople’s demands for political and social equality. White farmers and workers did not want to face economic or political competition from millions of formerly enslaved African Americans.

Most of the North’s white workers, though they did not want to compete with African Americans for jobs or consider them as equals, were unwilling to accept the continued domination of enslavers over the freedpeople. Most industrialists were committed to rebuilding the ravaged South as quickly as possible on free-labor principles, transforming formerly enslaved workers into wage laborers. And Republican Party leaders, intent on blunting the political power of the Democrats and former enslavers, needed the votes of newly enfranchised African Americans to build their party in the South.

The diverse objectives of Black and white people, North and South, resulted in sharp conflict and a growing sense of crisis. No group won all of its demands—least of all the freedpeople. For most, their quest for land of their own remained unfulfilled, although they did win important victories, especially citizenship and Black male suffrage. Even these gains engendered intense opposition among white southerners. So, too, did the increasingly radical policies of the Republican Party, and the efforts of some in the party to impeach President Andrew Johnson, the Tennessee politician who rose to power when President Abraham Lincoln was assassinated in April 1865.

Some white people came to believe that only terror could insure white supremacy in the South. The rise of the Ku Klux Klan after 1867 and the use of violence to subvert constitutional guarantees soon halted the freedpeople’s progress. Within a decade, the southern elite had reestablished its control, thanks in part to tacit support from moderate Republicans who came to dominate the northern party after 1870. Reconstruction ended tragically for the freedpeople, who saw their former masters returned to power through the combined force of vigilante violence and political compromise.

Meanwhile, the North and West were being transformed by technological change and the massive influx of migrants from the eastern United States and immigrants from abroad. Developments that began in the midst of the war accelerated after 1865. A transcontinental railroad system soon linked northern cities to western towns, mines, and farms. Industrial manufacturing multiplied as access to raw materials increased. Unprecedented numbers of immigrants filled the growing ranks of America’s postwar industrial working class. Economic growth and immigration further fueled westward expansion, creating new problems as well as increased conflict between settlers and Native Americans, Mexican Americans, and native-born white Americans, and among various Native nations.

The wartime coalition that had joined farmers, workers, and businessmen in the North broke apart in the face of these changes. Even as transportation and communication networks drew Americans across the continent closer together, differences of race and economic opportunity sharpened political divisions. The severe industrial depression that began in 1873 forced Americans to realize that their nation, too, was suffering the wrenching dislocations and class divisions already evident in Europe: increasingly, great wealth and opulence coexisted with grinding poverty and human misery. This widening gulf helped revive the labor movement.

Many sought to ignore this gulf during the celebration of the nation’s centennial in 1876, yet the following year America experienced its first nationwide industrial rebellion: hundreds of thousands of railroad strikers and their supporters brought the nation to a standstill. The end of Reconstruction and the nationwide railroad strike in 1877 closed out an era. Decades of conflict over slavery had ended, but the drama that pitted capital against labor continued, as did the struggles over the place of women and men, white, Black, and Native Americans, and native-born Americans and immigrants in the society, economy, and polity.