One of the hallmarks of Donald Trump’s presidential campaign was his promise to build a wall along the Mexican border to prevent illegal immigrants from entering the United States. His original plan was to force Mexico to pay for the wall by threatening to impose regulations that would stop the flow of cash remittances sent from undocumented Mexicans living in the United States to their relatives at home. In early January, however, President-elect Trump’s transition team signaled to Republicans leaders in Congress that his preference would be to fund the border wall through the appropriations pocess and have Mexico reimburse…