Its called absentee ballot. not mail in. I cant belive how many people have lost sight of this. BTW im pretty sure a shit ton of republicans did mail in also.
"They found that in presidential and midterm general elections between 1996 and 2018, switching to all-mail voting increased the percentage of residents who voted by 1.8% to 2.9%, they report today in Science Advances. When it came to the Democratic share of the vote, they found a tiny uptick in the share of votes that went to Democratic candidates for Congress, governor, and president—approximately 0.7%. But the difference was so small that the margin of statistical error means it’s possible there was no effect at all, Holbein says. “There might be a teensy, tiny effect on Democratic turnout.”"
https://www.sciencemag.org/news/2020/08/do-republicans-or-democrats-benefit-mail-voting-it-turns-out-neither
What about the president and military?
Its called absentee ballot. not mail in. I cant belive how many people have lost sight of this. BTW im pretty sure a shit ton of republicans did mail in also. "They found that in presidential and midterm general elections between 1996 and 2018, switching to all-mail voting increased the percentage of residents who voted by 1.8% to 2.9%, they report today in Science Advances. When it came to the Democratic share of the vote, they found a tiny uptick in the share of votes that went to Democratic candidates for Congress, governor, and president—approximately 0.7%. But the difference was so small that the margin of statistical error means it’s possible there was no effect at all, Holbein says. “There might be a teensy, tiny effect on Democratic turnout.”" https://www.sciencemag.org/news/2020/08/do-republicans-or-democrats-benefit-mail-voting-it-turns-out-neither