How much to worry about the US election unrest?

If Biden has a clear election night win, there might be local violence on the scale of Right Wing millitia groups attempting to take over locations (possibly successfully for a few months) a-la Cliven Bundy. There may be some violence, with casualties likely in the range of dozens nation-wide, but possibly reaching up to the hundreds in the 99.9th percentile worst case. 

If Biden wins, but not until all the votes are counted, probably double the above effects & risks.

If Biden gets more votes in enough states to have 270 electors, but some combination of lawsuits, direct violence, etc. by Republicans in various states leads to Trump "winning" then I would predict a substantial risk of direct violence by left-wing groups, perhaps 1% chance of Republican officeholders / operations being physically attacked in a sustained way. Likely a 75%+ chance of a dozen Republican election offices being damaged in violent protests nationwide.

If Trump actually gets more votes in enough states to have 270 electors, expect a continuation of current policy, risk, and violence, both in perpetrators and victims. 

IMO, the stakes are nowhere near as high as the candidates would have us believe.

In a normal election year, I'd say pretty confidently that it's at least 98% bluster: nothing will change all that much if A wins or if B wins. Most times I don't really even notice that there's a new president unless I'm trying to notice. With Trump on board, I'm still pretty sure that little of consequence will change (at least in the short term) if he does not win a second term. At the end of four years without Trump, I expect the larger federal government complex to be somewhat healthier than it is with him in office, and that's about it. I'm substantially less sure that he'll accept a loss gracefully, but I don't think there's really anything he can do about it. Even "his" "stacked" Supreme Court is bound by the law itself. If the (electoral) votes are for Trump, he wins. Else, he loses. It's pretty cut-and-dry. I've seen a couple of times now where somebody tried to have the results questioned (remember "pregnant chad"?), and still nothing has really changed. In the event of his loss, I expect he'll try to sue, make a lot more noise about the process being rigged against him (personally) using the same media that he cries about all the time, and eventually write a book have a book written about how unfair and broken this whole "democracy" thing is. Meanwhile, Biden will take power and start running things his way, which looks a lot like the old way (before Trump): still broken, but more subtly so. There will continue to be BLM protests as before, and (just like when Trump took office) there will be a rash of anti-the-new-president protests. Some of these will become violent (often after police provocation), but most won't. In a few months, we'll all go back to our regularly scheduled apocalypse. If Biden loses, I expect him to quietly concede the loss like a "good candidate" and go back to making a whole lot of no noise whatsoever like he was doing for most of the last few years, all while we get more of the "new normal" from the White House for another 4 years. The world probably won't end any harder than it already is doing.

And to be clear, Trump is not actually responsible for covid-19, or the orange skies, or Beirut blowing up, or racism and police violence, or named storms past the letter Z (or murder hornets, but they're not actually any more scary than those africanized honey bees from a while back, they've just got really effective PR). Only the details would have changed under another president. All this stuff will continue to happen under the next president, regardless of who "we" "select".

I doubt riots will get any worse after the election, and they're a local problem, not a country problem. If there's violence where you are, I expect it to be about the same afterward, but most people in the country aren't interested in violence and that won't change just because the current president stays in office for a few more years.

It doesn't matter if Trump and Pence respect the election result. If Trump loses the election, he's not the president anymore and the federal bureaucracy and military will stop listening to him. For a supposed-fascist, he's terrible at stocking the government with supporters, and the idea that the US military would support him in a coup is unbelievable.

It also doesn't matter if he wants to interfere with the election, because he can't. Presidential elections are run by state governments (and there are some strong constitutional barriers that would prevent anyone in the federal government from interfering with them).

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