Belgium has compulsory voting. (In many countries there is little or no penalty for not voting but “compulsion” is still an incentive. Of course you have the option of turning up and saying you want to turn in a blank ballot.)
Sweden has automatic voter registration. That’s probably a big help.
Encourage young people to vote: it may become a life-long habit.
Make elections consequential. In the U.S., out of 51 states only five or six have a real chance of affecting the outcome of a Presidential election. (Change the electoral college system if you want higher turnout.) Most House seats are gimmes for one party or the other. (This is due in part to structural flaws like gerrymandering.) Voters may not know the candidates for lesser offices. (Make communities more cohesive.)
Make elections consequential. On some issues, e.g. protection of citizens from financial abuse, both parties may appear to have sold out to Big Donor. Voters get discouraged.
Oh come on! I too would like to see a cite that vote by mail has higher voter fraud.
Oregon has had vote by mail for many years. Works great. The ballots are mailed only to registered voters. No one else. At their address when registered, no where else. So where are these fraudsters getting the ballots?
Are you counting someone filling out grandma’s ballot and having her sign it as significant voter fraud?
Something like this has been an issue in the UK: allegedly people went round old people’s homes and ‘helped’ the residents to fill in their ballots. This is compounded by electoral officers not doing their jobs properly and checking signatures.
A quick Google indicates that this may be an issue in the US.