President-elect Donald Trump’s vow to overturn an executive order that provides temporary protection from deportation to undocumented immigrants who were brought to the U.S. as children could cost the country tens of billions of dollars, a new study finds. Put in place by President Obama six years ago, the Deferred Action for Childhood Arrivals program has helped hundreds of thousands of young people – known as the DREAMers – come out from the shadows and get valid driver’s licenses, enroll in college and legally secure jobs.