This election cycle, former President Donald Trump has made one campaign promise the most prominent: Mass deportation. It is a long-standing vow. In 2016, Trump said he would deport the 11 million undocumented immigrants living in the United States. Once in the White House, he ordered sweeping worksite raids, enacted a ban on travelers from Muslim-majority countries, and deliberately separated migrant families, many of whom have yet to be reunited.