Drilling in on my data by month, it looks as if July or August, 2019, was the switch-over, with another big hit in Dec 2019 / Jan 2020:

   2018-1 *************************************************************************
   2018-2 ************************************************************
   2018-3 **********************************************
   2018-4 *********************************************************************
   2018-5 ***********************************************************************
   2018-6 *******************************************************************
   2018-7 ****************************************
   2018-8 ********************************************
   2018-9 ****************************************************************
  2018-10 *************************************************
  2018-11 *****************************************************
  2018-12 ****************************************************************
   2019-1 ************************************************
   2019-2 *************************************************
   2019-3 ************************************************
   2019-4 *******************************************************************
   2019-5 *******************************************************************
   2019-6 *****************************************************************
   2019-7 ******************************
   2019-8 ******************************************
   2019-9 ************************************************
  2019-10 ********************************************
  2019-11 ***********************************
  2019-12 ********************************
   2020-1 ************
   2020-2 ************
   2020-3 *****************
   2020-4 ************
   2020-5 *******
   2020-6 *******
   2020-7 ************
   2020-8 ************
   2020-9 *******
  2020-10 *******************
  2020-11 ********
  2020-12 *****************

(July seems to be an annual slump in HN -- NYT submissions for some reason, which confounds analysis somewhat.)

(Apologies to mobile readers ;-)

I for one won't upvote a paywalled article.

That's one hypothesis I'm considering.

It'd be interesting to, say, look at a number of sites which have gone paywall and see how that impact on HN front-page posts.

Off the top of my head, some of those would be:

- NYTimes

- WSJ

- Quora

- WaPo

- LA Times

If anyone has a handy list, especially with dates, I'd appreciate it.

Here's the top 40 "general news" sites with barplots by year. I know that NYT, WSJ, WaPo, LA Times, telegraph.co.uk, and possibly a few others have paywalls and may have implemented them over this period. Pastebin to spare readers here another monster text post, expires in a month:

<https://pastebin.com/raw/nmNXyE8G>

Paywall dates:

- NY Times: ~August 2019

- BBC: none

- The Guardian: none

- Washington Post: June 2013. <https://news.ycombinator.com/item?id=5829206> HN traffic actually rose. Tightened markedly in 2018: <https://web.archive.org/web/20171213135245/https://reason.co...>

- Reuters: April 2021 <https://news.ycombinator.com/item?id=26820053>

- NPR: none

- CNN: none

- Slate: 2015 (International readers) <https://news.ycombinator.com/item?id=9821492>

- Vice: none?

- LA TImes: Paywalled, 2012. <https://www.huffpost.com/entry/la-times-paywall_n_1299997>

- CNet: none

- Yahoo: none

- SFGate: 2015 <https://old.reddit.com/r/bayarea/comments/2sj78h/death_spira...>

- cbc.ca: none

- CNBC: none

- guardian.co.uk: none

- vox.com: none (though discussed)

- salon.com: none?

Mixed bag on impacts, though I suspect paywalls going up or tightening has a lot to do with FP story trends.