In the last month of the presidential campaign, former President Donald Trump is doubling down on his promise to carry out the largest mass deportation effort in American history. In Reading, Pennsylvania, last week, Trump drew fervent applause from a rally crowd after saying he would "get these people out" and "deport them so rapidly." In Aurora, Colorado, on Friday, Trump told rallygoers he would "rescue Aurora and every town that has been invaded and conquered." Immigration researchers, lawyers, and economists have pointed to immense constitutional, humanitarian and economic problems posed by Trump's oft-repeated pledge. But beyond the anticipated damage...