President Donald Trump has proposed spending billions of dollars to erect a wall on the U.S. border with Mexico and hire more border agents, but those measures would not address people who arrive legally and stay after their visas expire. Trump vowed during last year's campaign to finish building a system to record when visitors leave the country by using biometric identifiers, like facial or iris scans, but he has focused much of his attention on building a wall and hiring more border agents. Homeland Security's internal watchdog said earlier this month that immigration agents waste their time logging in and out of archaic computer systems while trying to track down foreigners suspected of overstaying their visas only to find out later that many visa holders have left the country.