If Voting By Mail Increases Turnout, Why Aren't More States Using It?

We know that vote-by-mail options are effective at increasing turnout, so why aren’t more states using it? Partisan explanations don’t explain why states are not adopting the easy and cost-saving fix; for example, although some believe the measure may favor Democracts, it depends largely on the race in question: for example, incumbent Democrat Mark Udall lost his Senate seat in the first-ever vote-by-mail election in the 2014 Colorado midterms.

The mail-in ballot option is becoming more common in state and local elections, but few states allow it for the presidential vote. A likely culprit for why this method is not used in all our elections is that our current system discourages both parties from pushing turnout except in the dozen-or-so swing-states. Those states provide the path to victory and votes there are far more influential than all the votes cast in the remaining 38 states and D.C. A national popular vote would change all of that and make it imperative to get out the vote everywhere. Your vote should matter, and you should have options that make it more convenient to vote!