There is some nuance to mail-in elections. The state laws are all different and not at all uniform. I live near the border of two mail-in states. In one, they count all ballots regardless of when they are received, as long as they are postmarked by midnight on election day. In the other one, they have to receive all the valid ballots by 8pm on election day. Any late ballots are invalid. Things start getting weird when you look at trends and statistics. If Republicans tend to vote in-person on election day, or drop off their ballots at a county ballot box on election day (not before), then you have a one-time pulse of Republican votes. If Democrats tend to take their sweet time and mail in their ballots, you could have a long wave of low-level activity that might continue up until election day or even afterwards, if it's legal in that state. In my area, counties have different election rules. In one county, they count all ballots as they come in. So they can have a large count already completed on election day, and continue to count the later ballots for days after the election. In an adjoining county, they do not count ballots at all until the end of election day. So it might look like a Republican candidate is winning statewide, but later on there is a blue wave and brings the Democrat to a higher tally. We do know that voter turnout was extraordinarily high, in part due to the recent SCOTUS decisions and the galvanizing actions of politicians. So there may be a few surprises yet to come. Stay tuned.