The most practical fix is to make voting by mail a clear and free option for every eligible voter in the country. This means, at a minimum: printing tens of millions of mail-in ballots and envelopes; ensuring that all registered voters receive one automatically, can request a replacement if they don’t, and can return it by Election Day; and finally, having the human and technological resources, like ballot scanners, available to count those votes quickly and accurately.

The good news is that we already have evidence that voting by mail works well. In five states — Colorado, Hawaii, Oregon, Utah and Washington, most or all votes are cast by mail; in three others more than half are. In all, nearly one-quarter of all voters cast ballots by mail in 2016.

The experiments in the states have yielded several key findings: First, turnout is significantly higher nearly everywhere voting by mail is used. Second, voters of all political persuasions use it and like it. Third, it’s safe and secure. Bar codes allow for ballot tracking and validation. And states that use vote-by-mail have encountered essentially zero fraud: Oregon, the pioneer in this area, has sent out more than 100 million mail-in ballots since 2000, and has documented only about a dozen cases of proven fraud.

The success of mail-in voting in these states is encouraging, but to pull it off on a national level, preparations must begin today. In 2018, 31 states had fewer than 15 percent of their ballots cast by mail. Switching to all or nearly all voting by mail will require printing at least 70 million additional ballots.

These ballots will have to be ready to go out by Labor Day, less than six months from today. They must be postage-paid, so that no one has to pay a penny to vote, and there need to be enough machines and poll workers available to start counting ballots as soon as they come in. Signature-matching software can help ensure ballots are coming from the voters they were sent to, without introducing partisan bias into the process. And where signatures don’t match, voters should have an opportunity to fix the problem and cast a provisional ballot if necessary.