... certification by all 50 states and the District of Columbia of the votes of 155,485,078 qualified Americans, without prejudice as to whichever legitimate method of voting they chose. (Donald Trump's mail-in ballot was as valid as any fellow citizen's who had waited hours in a line at a polling place.) 306 - 232
Trump had voted by mail earlier. On Monday, Aug. 17, the Palm Beach County Elections Office reported that it had received a mail-in ballot from the president, as well as from first lady Melania Trump in the Florida primary election. Trump had no problem with taking advantage of the mail-in method himself.
Regardless of whichever legitimate method an Americans chose to vote, all states - with the exceptions of Louisiana, Georgia, South Carolina, New Jersey, and Delaware - use paper ballots, at least as a back-up, to allow for recounts and audits to insure accuracy.