United States

Requirements that international travelers and migrants prove vaccination against certain diseases are about as old as vaccines themselves. In some cases, vaccine certificates predated the existence of government-issued passports. This article explores the history of these requirements, which began with smallpox and have since been applied for diseases including cholera, polio, yellow fever, and, recently, COVID-19.

The United States’ controversial Title 42 migrant expulsions policy will come to an end in May 2022, after more than 1.7 million expulsions over two years. The COVID-19-era public-health restriction ushered in an unprecedented period of mass expulsions, including of would-be asylum seekers, at the U.S.-Mexico border. Unwinding the policy will be complicated amid predictions of a significant increase in unauthorized migration.

What’s in a name? Terms used to refer to people crossing international borders are frequently debated and often evolve, amid efforts to shape the narrative and changing political realities. This article explores the history and evolving use of terms such as "migrant," "refugee," "illegal immigrant," "unauthorized immigrant," and more.