WASHINGTON—Since President Trump took office on Monday, he has issued a flurry of directives to expedite the removal of millions of undocumented immigrants from the U.S.Immigrant groups are bracing for large raids,

President Donald Trump has already inundated the country’s immigration system with enough changes to create immediate impacts along the border and across American cities. Thousands of migrants trying to gain entry in the United States to seek asylum using the Custom and Border Patrol’s mobile app — set up by the Biden administration to deter migrants from crossing illegally — had their appointments canceled,