I was specifically mentioning that when you mentioned the depression you were, by your own evidence given in this post, several decades off. Like the original thread says, brisket (probably die to its availiability as a packer) was not popular rather recently..... really until the late 50's. Sure, you can find a place that has been serving a long while (Angelos in Fort Worth has always served it which opened in 1957) and Jetton only used it at the end of his carreer.
The depression was NOT contributor
to the rise of brisket as an accessible cut to BBQ NOR would WWII
be at all due to the rationing. After the War, it took a great while for the economy to get moving again and the rise of the BBQ resturant would have to wait until the mid 1950s. Right after that the meat packers began the consolidation changes that have brought us to what we have now. In order for something to catch on like the OP is suggesting (which denotes it was not poplar before) the cut has to be easier to get than just butcher shop..... and that came with the rise of suburbia and the death of the meat markets. The product was always cheap... but it took the packing process to evolve a little better (where you could order, say, 40 briskets every day and get delivered nothing else) for the cut to be the staple of beef bbq its known as today.
There is a dissertation on the strange rise on cost of the skirt steak in the late 70's and early 1980's that came out of Texas a and m that covers some of the concept as the author used the brisket as a model for comparision. This was doen because there was a mysterious rise on the cost of the skirt steak which was attributed to both the ability to get these separate and the rise of the "fajita" that begun around this period.
You should tweak your thesis statement..... to....."Since the way to make a tender brisket is a comparative constant regardless of era, and being that the cut has always been an economic cut, supply capability is the sole reason it has become popularized."
While the quote from Mares is certainly a primary source, we all know the brisket can be cooked at the same temp as a quarter or shoulder and be a thing of beauty.
Originally Posted by Boshizzle
I'm sure some reastaurants were cooking brisket before the depression but it and WWII were big drivers. Edgar Black, Jr. said that when he started cooking BBQ for his Dad after WWII there weren't as many as half a dozen other BBQ places in Texas serving it.
Also, the book Republic of Barbecue - Stories beyond the Brisket has some interviews from old time TX BBQ cooks where they discuss brisket.
For example, Vencil Mares is quoted as stating that back in the 1940's "Them days, they didn't hardly ever cook briskets. They didn't know what to do with them. I remember when they was thirty-nine cents and people didn't even want them."
Bobby Mueller said that he couldn't get boneless briskets until the 1960s.
So, economics and supply capability did play a big part in popularizing brisket.