The 19th century was a time marked by territorial expansion, political upheaval, social reform, and rapid population growth in the United States. Between the aftermath of the American Revolution the late 1700s and the rise of American imperialism at the century’s end, the United States evolved from a fledgling post-colonial republic into a continental empire and emerging world power. Across these decades of change, music was both a reflection of and a participant in national identity, social upheaval, and everyday life.

At the beginning of the 1800s, the United States was a small, agrarian nation confined largely to the Atlantic coast. But over the course of the century, the country expanded dramatically in both size and population. The Louisiana Purchase of 1803 was a monumental land deal in which the United States acquired approximately 828,000 square miles of territory from the Napoleon led France, effectively doubling the size of the nation. This vast expansion included land that would become all or part of fifteen future states, stretching from the Mississippi River to the Rocky Mountains. It opened up the interior of the continent for exploration, settlement, and economic development, fueling westward migration and intensifying debates over slavery in new territories.

Soon after, the War of 1812 (1812–1815) In tested the young nation’s autonomy and determination in a renewed military conflict with Great Britain. Tensions with Great Britain flared over issues such as trade restrictions, the impressment of American sailors into the British Navy, and disputes over territorial expansion in the Northwest. The war featured significant battles such as the burning of Washington, D.C., and the successful defense of Baltimore's Fort McHenry, which inspired Francis Scott Key to write the poem that became "The Star-Spangled Banner." Although the Treaty of Ghent ended the war in a stalemate, the conflict generated a surge of national pride and reinforced a uniquely American identity, especially through patriotic music and folklore. Later, the Mexican-American War (1846–1848) arose from tensions over the U.S. annexation of Texas and the desire for westward expansion under the ideology of Manifest Destiny. Following a series of armed conflicts, the war concluded with the Treaty of Guadalupe Hidalgo, through which Mexico ceded nearly half of its territory to the United States. This included present-day California, Arizona, New Mexico, Nevada, Utah, and parts of several other states. The acquisition not only expanded U.S. territory significantly but also brought diverse cultural influences into the national fabric, further shaping the regional variations in music and identity that would evolve throughout the century.

This geographic and demographic growth was accompanied by massive shifts in transportation, technology, and cultural identity. As Americans moved westward and new states joined the Union, a more diverse range of regional cultures and musical practices emerged. The 19th century laid the foundation for what would become the distinct traditions of American popular music, shaped by migration, industrialization, and the interplay of different communities and identities.

By the end of the 19th century, the American popular music landscape had become both national in scope and commercial in structure. It was a period defined by contradiction: artistic innovation alongside cultural appropriation; mass participation alongside systemic exclusion; sentimentality alongside satire. This chapter explores the major genres, performers, and practices that shaped American popular music in the 1800s not solely as entertainment, but as a window into the social, political, and cultural life of a growing nation in flux.