A federal judge recently halted an executive policy by Texas Gov. Greg Abbott (R) that would have allowed state troopers to intercept cars suspected of transporting migrant passengers. Abbott claimed that this policy was necessary to enforce immigration laws and protect the state from the spread of the coronavirus. The Department of Justice intervened, however, because immigration policy is supposed to be under the purview of the federal government. As this shows, a battle is playing out in surprising ways between states and localities and the federal government about who has the power to control immigration policy.

It’s the revival of a much older debate about where this power rests. Today the national government has definitive authority to manage the entry and exit of people who cross national borders. But it was not always this way. For almost a century, from the country’s founding until 1882, the states and localities had control. And the history of state and local control over immigration is deeply rooted in a Constitution — and federal system — that was indelibly shaped by slavery.

Immigration is not the only issue to generate confusion and debate about the division of power. The United States has a federal system of government where different levels of government must share power. And while the Constitution established a blueprint saying so, the details have had to be filled in over time. The location of the dividing line between the authorities of the two levels of government, which government has responsibility over a policy area and when the national government gains exclusive control, has been decided by the politics of every era.

Enslavers greatly influenced the compromises in the Constitution. Enslaver interests worked to sharply delimit the boundaries of federal authority over slavery and to secure assurances that slavery would remain under local rather than national regulation. One way this goal was accomplished was to divide policy areas by subject matter jurisdiction. Southerners insisted that slavery was to be a state and local matter, striving to confine national power to foreign policy, commerce, defense and finance.

The division of labor over policy areas was underwritten by the “police powers” doctrine that derives from the Tenth Amendment of the Constitution. Under this doctrine, any policies regarding health, safety and morals were designated to local control. Southern and northeastern states each had their own regional interpretations of what “police powers” encompassed. Before the Civil War, these states interpreted these powers quite differently, depending on their individual state’s needs.

The federal government had little power to regulate people’s migration and movements — whether from other states or foreign territories — because doing so constituted a threat to slavery in the South and a threat to the northeastern states defending against the entry of large numbers of poor, sickly or disabled migrants.

For example, eight slave states between 1822 and 1857 claimed the authority to regulate the entry and movement of free Blacks, including free Black sailors from foreign and domestic ships arriving in southern harbors. These restrictions that they imposed, they alleged, were out of concern that free Black people were “moral contagions” who would intermix with the enslaved population and foment insurrection. By 1857, all the coastal slave states from South Carolina to Louisiana to Florida had laws authorizing the arrest, incarceration and sometimes sale into slavery of foreign and domestic free Black sailors. The South viewed these laws — in a sense, migration control laws — as rooted in the constitutional police powers and necessary for states to preserve public safety and internal security.