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Incidents of Customs and Border Protection (CBP) agents asking for the citizenship status of passengers on Amtrak trains and Greyhound buses are terrifying—and not even remotely new. Advocates have condemned reports of immigration agents demanding papers from passengers as far back as the Bush and Obamaadministrations. What advocates note is new, however, is the frequency at which these questionings are now happening, most recently in Florida. But how, you might ask, does Border Patrol have the authority to do this? Because of an “obscure law” passed by Congress decades ago:

Legislation from 1946 gives agents the authority to search any vehicle near an “external boundary” of the United States, and subsequent regulations defined that area as within 100 air miles of a land or sea boundary. While that may sound like just a sliver of the United States, 9 of the country’s 10 most populated cities lie within the so-called 100-mile zone, and about two-thirds of Americans live inside of it, according to the ACLU. Ninety-seven percent […]