The Civil War and Reconstruction transformed immigration policy in the United States, marking the transition from a sub-national to a national policy for regulating the admission, exclusion, and removal of foreigners. Before that turning point, Congress played almost no role in regulating immigration, other than naturalization policy (for white people) and passenger acts setting conditions on ships. The Civil War eliminated some of the worst abuses of the old state-level system. Ironically, however, the newly empowered federal state created during Reconstruction could restrict immigration much more comprehensively than any state—as Chinese laborers soon discovered to their detriment.
In the era of slavery, states and towns used their police power to control mobility within and across their borders and set their own rules for community membership. In the Northeast, states and cities imposed taxes and bonds on foreign paupers. Ship captains passed along the cost to passengers in higher fares. Local jurisdictions deported the poor out state and sometimes overseas. In the Old Northwest (today’s Midwest), state and territorial governments used bonds and taxes to exclude and monitor free Black people. Southern states policed the movement of African Americans, both free and enslaved, and passed laws imprisoning black sailors visiting from other countries and from other US states. These local measures rested on the states’ sovereign power to regulate their internal affairs. Insofar as they affected foreigners, they constituted the immigration policy of the United States in the antebellum era.
When it came to regulating mobility before the Civil War, local police power prevailed over federal commerce power. Defenders of slavery supported fugitive slave laws but resisted any other form of federal authority over mobility across and within their borders. If Congress had the power to control immigrant admissions, they feared, it could potentially use that power to control the movement of free black people and perhaps even the interstate slave trade. Migration, in other words, presented a political and constitutional problem in a slaveholding republic.
The Civil War, with the secession of eleven states from the Union and the abolition of slavery, removed the political and constitutional obstacles to a national immigration policy. Yet, in the absence of slavery, Congress would not have regulated—let alone restricted—immigration earlier. Even though the abolition of slavery cleared a path for the emergence of a national immigration policy, in other words, it did not make that policy inevitable.