A variant of (3) would be election months. In Virginia, where I vote, they have (what they call) a version of absentee voting where a person who expects to be absent on election day can go into a government office on the weekend for a couple of months before the election and cast their vote in person that way. We could expand that - every day of the week for October and maybe September, an office is open to accept in-person votes. We could even randomly assign each voter a particular day in that month(s)-long window to come in and cast their votes, so that we don't end up with too many people in the same physical space on any one day.
LOL -- I actually live in VA as well and 3 is really my preferred approach. I just think it should be fairly simple to accomplish, less upfront work I think. It will likely also reduce the challenges (see mfoley's link) so keep the final results on track. But I've never actually voted (so kind of an odd question for me to be asking I suppose) and was completely unaware of that option.
Somewhat unrelated but perhaps might be interesting. If all states were to follow that plan -- allow small numbers to come in an vote -- if we allowed voters themselves to reserve an open voting slot in the 2 months before the official election day what would we see. I wonder what insights that might give value of campaigning in the last couple of months and what type of voter is influenced. Would those results match existing expectations?
My dad is an election law professor and he's been talking nonstop about this for weeks... this is his article on it
Some states (Washington, California) already have mail-in voting available for everyone, I don't think there are any federal legal barriers to expanding it.
Relevant Metaculus question: Will the US hold mass-turnout elections for President on schedule in 2020?
Saw a news story this morning about possible using mail in ballots for the elections and concerns about it not being a fair process (disadvantaging Republicans). Leaving that aside it does seem that we might want to consider a plan for November just in case. (ROK is running into some difficulties with its upcoming elections it seems.)
I can think of three possible approaches, perhaps others are possible.
1) Use the mail-in function. That is already a legal process but would need to be extended to locally present voters not just those elsewhere. Down side here would seem to be mail in votes are always questioned it seems as potentially fraudulent, perhaps without reasonable cause as well.
So if we decided we still need social distancing for the election mail in votes will accomplish that but will likely delay counting and ultimately identifying the winner as I would expect a lot challenges even in not that close a race -- you need a wide margin where all agree the result was as expected or too big a difference to be counter error or fraud.
If we take that route we probably need to tell everyone to submit their paper work and hire election staff to vet the applications.
2) On-line voting. Well, we do have electronic voting machines. There are certainly ways to make that possible but could it be done in time and securely? Suspect this would both be executed very poorly and be open to even more fraud or other manipulations than mail in voting. It attempted I would expect the final announcement might be even more delayed than for the mail in votes.
3) Election Week rather than Election Day? In this approach nothing changes in the voting process other than reducing the number of people at the polls at any given time -- so the longer period of time for people to cast their vote. Down side is that might require some type of legislation. It would also need to be planned out in advance (by whom?) so everyone knows the date (and perhaps time) when they are allowed to cast their vote.
[Note, I've not offered any reason why or any estimate on if this would be necessary. I suspect those here can make their own assessments on that. However, this is not something we (the people) would want to wait to the last minute. Additionally, perhaps this would allow the politicians to start focusing on politics rather than pandemics and get them out of the medical experts way ;-) ]