News. Probably during H.W. Bush.
Here's an article from 2008 talking about the 2 quarter rule of thumb. Apparently it's been around since 1974.
https://money.cnn.com/2008/05/05/news/economy/recession/
Here's one from 1998 using the 2 month definition.
https://money.cnn.com/2001/09/28/economy/economy/index.htm
Here's the NYT defining it the same way in 1974. From the text:
The bureau considers a recession to have occurred when there has been an ettended substantial, and widespread decline in aggregate economic activity—or, duration, depth, and diffusion. The bureau has not specified the breakpoints which distinguish recessions from milder slowdowns. Its experts depend rather on comparisons of current cyclical trends with what happened during previous business cycles, a process that involves some qualitative judgment and interpretation of cyclical trends.
Seems the NBER was pretty wishy washy about it back then too.
The bureau has not specified the breakpoints which distinguish recessions from milder slowdowns.
If it's been around since the 1920s, why isn't it mentioned in 1974? Maybe the NYT dropped the ball.
The NYT goes on to opine:
A rough translation of the bureau's qualitative, definition of a recession into a quantitative one, that almost anyone can use, might run like this:
In terms of duration—declines in real G.N.P. for 2 consecutive quarters; a decline in industrial production over a six‐month period.
There's your 2 quarters boundaries, back in 1974.
https://www.nytimes.com/1974/12/01/archives/the-changing-bus...
It's pretty evident that both have been around a long time and politicians, their news allies and political operatives push whichever one is most convenient. In today's case, the (current?) NBER definition means we aren't currently in a recession (yet), which benefits the current sitting president, briefly.
FYI, I can't seem to find in your first link from 1983 where it actually defines a recession. Perhaps you can quote it. I stopped reading your links after the first one didn't seem to have any references to your claim, but I might have missed it. My eyes started to glaze over a bit, business cycles in 1980 is pretty dry reading.