WASHINGTON — President Donald Trump signed an executive order Friday directing federal agencies to implement new safeguards aimed at ensuring that only U.S. citizens vote in federal elections, including mandatory cross-checks of voter rolls and enhanced tracking for mail-in ballots. The order instructs the Department of Homeland Security to construct and maintain comprehensive lists of verified U.S. citizens drawn from federal records. States would be required to match their voter registration rolls against these lists at least 60 days before any election. In addition, all mail-in ballots must be sent in secure envelopes featuring unique barcodes issued by the United