In 1903, friends of poet Emma Lazarus installed a plaque on the Statue of Liberty in New York Harbor bearing text from one of her poems. It read, “Give me your tired, your poor, your huddled masses yearning to be free.” Yet at the time the poem was added to the statue, free and unfettered immigration – such as it ever was – was already in the past, and an increasingly restrictive regime of migrant policing and border control had begun to emerge. Over the course of the four decades that followed, the US government laid the legal and bureaucratic groundwork that would govern migration in and out of the country and define the concept of border security for the next century. Ever-present surges of nativism and concern over the potential threats to national security posed by unregulated immigration helped to guide the direction of these changes. In these decades, the United States developed a comprehensive body of immigration law, consolidated control over national borders, entrenched extraterritorial control over visas, and came to consider migration more explicitly in terms of national security, economic strength, and demographic solidarity. Alongside these new controls – and sometimes in spite of them – millions of new immigrants poured into the United States, changing the cultural and demographic landscape of the country and complicating definitions of what it meant to be an American.