Suppose, hypothetically, someone was planning to commit electoral fraud in Montgomery County, PA, in favor of the Democrats.
By 5:43am Wednesday morning after election night, Trump is ahead by 618,840 votes, with counting still proceeding. So far, Montgomery County, PA had reported 148,100 mail votes (running 24.4% Trump, and 74.9% Biden) and 388,018 votes total (running 40.8% Trump, 58.2% Biden) (Raw data, Fact 6). Montgomery County has the third highest expected number of votes of all counties in Pennsylvania (Raw data), so they’re one of the few places in a position to be large enough to possibly affect the outcome via fraud. Pennsylvania was always going to be close, and so the fraud perpetrators wanted to keep as many uncounted ballots as possible in reserve, so that if needed they could produce fraudulent ballots and run up the statewide total for Biden. But crucially, the perpetrator didn’t know in advance exactly just how many ballots would be needed to win the election. So they kept a fair amount back, holding 23% of precincts still in reserve. (Raw data) The amount of mail ballots they had counted by Wednesday morning relative to Edison forecasts is relatively low in the data.
On Tuesday night, the county had held a press conference pre-announcing an approximate number of absentee ballots they’d already collected, but somehow not counted. Some people wondered if it might look weird for a county to hold a press conference on election night rather than just count the votes, but ostentatious displays of transparency make great cover, even if just by unrelated groups taking advantage of them.
Over the course of Wednesday, counting goes on. But for some reason, and this possibility is somewhat open to interpretation, somebody screws up and enters each new update into the “in-person category.” It’s hard to know quite why this happens, but you can imagine different variations at this point. In one, it’s just a pure screw-up – someone doesn’t know how the scheme works, and enters the wrong vote type in a database, then has to correct it later. In a different variant, it could be pre-planned – a great cover story if you need to make extra changes on Wednesday night is “these obvious mail ballots, which were pre-announced, have to be changed to the correct category.” In any case, there isn’t a single update made to mail-in ballots over the day on Wednesday (Raw data).
Wednesday night arrives, and organizers of the fraud realize they now have not one, not two, but three problems with their fraud scheme.
Firstly, statewide, Trump is still up by 164,414 ballots. They need to get more votes from somewhere, or he’s likely to win Pennsylvania and maybe the White House. Commit fraud for the winning side, and they’ve got a good chance of getting by. Commit fraud for the losing side, and they risk winding up in jail. As one of the three biggest counties in Pennsylvania, they’ve got to play a big part.
Second, one way or another, they’re going to have to correct the ballots that were classified as “in-person.” The county had pre-announced details of how many mail ballots were still to be counted, so it would look very strange if this number were to radically change. In general, in-person ballots have a clearer paper trail than mail ballots. So if they’re going to have a chance of not getting caught, they need to do it with mail ballots. In-person ballots are delivered by voters to the actual polling booths around the county, but mail ballots throughout the county have all been sent to a single postal address (Fact 4). This gives them not only one place to control everything, but one single place where they can hide the evidence by mixing up genuine and fraudulent ballots afterwards. Furthermore, the decision to only add totals to in-person votes has left them with a series of updates that look very strange. (Fact 7, Fact

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Third, in their effort to produce a smooth glide to the finish, they’ve already spent most of the precincts. They’re now up to 492,027 total votes that have already been announced, or 97.6% of the Edison estimated total (Raw data). They can’t push the total number of votes too high, or it’s going to raise too many eyebrows – high turnout smells like election fraud. They can use mail ballots for the rest, but with just 12,210 estimated votes left before hitting the Edison expected turnout, they run the risk of not having enough.
So between Wednesday night and Thursday morning, they decide to do several things at once.