What was the most important election of the 21st century?

Yglesias makes the case for 2016, with one reason in particular standing out:

Biden would also have a huge legacy on the courts. Replacing Antonin Scalia with even a relatively moderate liberal like Merrick Garland would’ve been a huge deal. But what’s more, Biden would have been able to fill all the lower court vacancies that McConnell spent years holding open. For the first time since some point in the 1970s, the judicial branch would end up under solid Democratic control.

Right now, the sobering reality is that there is just no clear path — ever — to Democratic control of the courts. I’m not saying it won’t happen, just that it’s not clear how it would ever happen. With six seats, the ability to strategically time retirements, the GOP structural edge in the Senate, and Justice Breyer being annoying, it’s not clear what the path is. But it is clear what the path was — win in 2016.

This hinges, of course, on a particular counterfactual:

For the purposes of our counterfactual, let’s say Biden does about 1.5 percentage points better than Hillary Clinton did, securing a comfortable Electoral College majority.

Applying this +1.5 coattail adjustment to Senate races, Democrats also pick up seats in Pennsylvania and Missouri.

Let’s grant the “Biden/O’Malley/Bernie woulda won” premise — unknowable but certainly plausible. The issue here is that +1.5% coattail adjustment. Dems winning the Senate back in 2016 depends on that figure being at least that high or more. There’s a little wiggle room in PA, but in Missouri Kander (who lost by 2.8%) would have needed almost all of that swing. Even if you assume another candidate would have done 1.5% better than Clinton — not ridiculous, although it’s a lot — Kander already ran so far ahead of the Dem candidate I have a very hard time believing that there were enough gettable votes out there to close a nearly three-point gap. (McCaskill lost by nearly 6 points in a much more favorable national context two years later.)

And if Dems don’t win the Senate, everything plays out very differently. Scalia’s seat still isn’t filled, McConnell probably stops any domestic agenda, and then the Dem incumbent would fave a pandemic election with even more Republican sabotage and no stimulus. Still better than Trump winning, but…not great.

So while 2016 was certainly very important, I think I’ll stick with 2000. Avoiding Iraq (and possibly 9/11 itself), as well as Alito is Gore wins again, is an awfully big deal.