I think this may be to commemorate the passage of the District of Columbia Organic Act of 1801, which placed the District under Congressional control. This removed people's citizenship as part of either Maryland or Virginia, meaning they no longer had voting rights.

I'm a transplant, so I didn't really think much about the date. But the Council of DC mentioned it on Twitter today here.

I went there this past weekend for the first time. I really enjoyed the food, and it was such a cool vibe inside. Definitely would recommend!

Glad I could help OP :)

>Many political appointee jobs went unfilled, there wasn't a surge of new young aspiring staffers etc.

Is that true? I vaguely remember reading an article along the lines of OP's point that presidential administration's do affect DC culture a little bit. Because the Trump Team was full of political outsiders, they didn't pick up a lot of the think tankers and other former administrative officials like you would expect. And look at how many Trump staffers were young people. Like, wasn't the deputy head of his personnel office like an undergrad from GW or something?

As I said, I remember reading some article about how most of the Trump staffers ended up moving to Navy Yard and Southeast. But I'm not so familiar with that, and it should be pointed out that there's been some development in those neighborhoods, so of course new people to the city would gravitate there.

ETA: I used to read a lot of Politico back in the day, and this article sounds about right. I could be wrong, but this is what I was thinking of.