History does not repeat itself, even if it sometimes rhymes. But, as the president calls for 15,000 new ICE and border patrol agents to bolster an already hypertrophic deportation machine, it is worth pausing to reflect on an earlier moment of fugitivity and federal power, of crisis and resistance: the years following the passage of the Fugitive Slave Law of 1850.

The resistance had its roots decades earlier, when a despised and subordinated minority—northern free blacks—inspired the enduringly unpopular interracial social movement called abolitionism. That movement formed a periodic, conflict-ridden coalition with a much larger group of whites who opposed the extension of slavery but did not seek its abolition. The radicals drove the non-radicals steadily forward in defense of fugitive slaves, defying both federal law and the warnings of the major political parties. In some places, such as Boston, that defense and the federal reaction to it were so fierce that it gave birth to a new politics of race, slavery, and freedom.

That history is over. It cannot directly shape how a resistance movement behaves today. But an account of its roots, complexities, and achievements may suggest how radicals can shift the field of political play and debate in their direction, pursuing their goals while persuading the persuadable. At the very least, it is one of the United States’ great freedom songs. It may do us good to learn the words.

The struggle of the 1850s began in and drew its animating energy from African Americans’ analysis of their own circumstances. Slavery hung a shadow over the lives of free black people, even in places where slavery had long been legally abolished, such as Massachusetts. There, African Americans possessed nearly every formal right on the same basis as the “free white persons” legally eligible for immigration and naturalization. But African Americans commonly experienced northern freedom as mocking, hostile, and violent. For the fugitive slave Frederick Douglass, liberty in Massachusetts included a constant, oppressive awareness of being perceived as an inferior. “Prejudice against color is stronger north than south,” he declared; “it hangs around my neck like a heavy weight. . . . I have met it at every step the three years I have been out of southern slavery.” Even in Massachusetts, African Americans were barred from nearly every avenue of economic or educational advancement. Railroad companies segregated black passengers in Jim Crow cars, a policy their conductors enforced with violence. State officials ejected free blacks from official processions, and ruffians chased them from Boston Common. The foremost form of popular entertainment, the minstrel show, mocked their appearance and aspirations. No wonder northern black activists bleakly called themselves “the nominally free,” or “the two-thirds free.” One African American newspaper was entitled the Aliened American.

In this sense, the free black people of the mid-nineteenth century prefigured the struggles of later generations of what historian Mae Ngai calls “alien citizens.” Ngai’s analysis reveals how the U.S. citizenship of native-born Americans of Chinese, Mexican, Japanese, and Muslim background has in practice been limited or nullified by what many consider to be their unalterable foreignness. The radical black activists of a century and a half ago well understood that their compatriots regarded them mainly through the prism of their racial association with slaves. So it has been since, for Chinese Americans figured as unassimilable aliens, Japanese Americans assailed as members of an enemy race, Mexican Americans dubbed “illegals” and rapists, and Muslim Americans branded terrorists. Even those formally vested with citizenship cannot escape the gravitational drag of their racialized association with a dangerous and foreign otherness. Even the mildest formulation of alien citizenship tells the tale: “Right, but where are you really from?”...