The intensifier 'pure D': where and when did it originate, and what does the D stand for?

A very quick google led me to this post on WordWizard by user Ken Greenwald

...The evidence, however, looks pretty strong to me for the probable origin provided by the Dictionary of American Regional English (DARE):

PUREDEE adjective, adverb. Also PURE-D, PURE DEE OLD, PURE O.D., PURE OLDEE, PURE-T [[all forms in lower case]] [Probably originally euphemism for pure damn(ed)] chiefly South and South Midland, U.S.: Genuine, real, just plain; very, really, completely.

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Here’s what Cassell's Dictionary of Slang had to say, which is much less convincing, based on the quotes that follow:

*PURE-D adjective (also PURE-DEE, PURE IDEE) [1950s and still in use] (U.S.): Complete, absolute, utter [‘pure,’ adverb + ‘D,’ adjective?]

D adjective [early 19th century]: Excellent, wonderful, first rate. [? abbreviation for ‘dandy’ (late 18th century and still in use): first rate, excellent, a general term of approbation].*

Harold Wentworth, American Dialect Dictionary (1944) notes two early instances of "pure D" (and one in which "pure bee" may serve as an intensifier)—all from 1941—in its entry for pure, though it doesn't offer any insight into the question of what the D stands for:

pure. ... 2. adj. Good, perfect; veritable, downright, 'regular.' [Relevant examples:} 1941 A pure bee swarm of o' chaps. [James] Still '[The] Proud Walkers.' 1941 it takes a pure D humdinger to hunt birds .. if a dog's got pure D hoss sense & a fellow's got bat brains, he can train the dog to hunt birds. J. Street in S[aturday] E[vening] Post Dec. 6, p. 110. 1941 s.e.Miss[issippi] Laurel I'm pow'ful fond of Woody. He's a pure D man .. He .. won his case. He's a pure D man .. Mama has got pure D gumption. J[ames H]. Street [In My] Father's House 148–65, 346.

I couldn't find a readable edition of Still's "The Proud Walkers" to provide additional context for the "pure bee swarm o' chaps" example, but I suspect that "pure bee" in that case is tied very tightly to "bee swarm" and isn't a variant of "pure D." I did find the examples written by James Street, however—in "Weep No More, My Lady" and in In My Father's House, which interested readers may consult for greater context.

Perhaps the most noteworthy thing here is that Street seems to use "pure D" as a positive intensifier of admirable things: having "hoss sense," being "a man," and having "gumption." But in the examples from later decades that I cited in my original question, the intensifier is associated with negative qualities—"crap," "invention" (in the sense of "untrue story"), "fool," and "bull." So if Street was reflecting current usage in his 1941 use of the modifier, usage of "pure D" may have shifted from positive situations to negative ones over the years.

The examples from Street move confirmed use of "pure D" as an intensifier back to 1941. Searches of the Elephind and Library of Congress newspaper databases (the latter covering newspapers from the years 1789–1922), however, did not turn up any matches for "pure D" or "pure-D."

Stella Hughes, Hashknife Cowboy: Recollections of Mack Hughes (1989) has this glossary entry:

pure-dee Texas or southern phrase meaning pure damn.

Hughes, uses "pure-dee" nine times in the body of this book—eight times (negatively) in the expression "pure-dee hell" and once (positively) in the expression "pure-dee luxury."

R.Scott Brunner, Carryin' On: And Other Strange Things Southerners Do (2001) has this:

Pure-dee: a more polite form of the well-known expletive "pure damn," which of course means "unmitigated": "It's just pure-dee stupidity to think Vanderbilt could win the SEC."

Here the negative connotation of the expression is unmistakable. (The "SEC" in the quoted example is "Southeast Conference," a powerful collegiate football conference that Vanderbilt University continues to be very unlikely to win any year soon.)

Inspired by these instances and by Richard's answer, I also ran Google Books searches for "pure damn" and "pure damned." Those searches yielded several dozen matches—but only one from before 1993. From the Anaconda Copper Mining Company, Bureau of Safety, Anode, volumes 9–10 (1923[?]) [combined snippets]:

Something must be done to restore the feeling of safety. I turned over most things in my mind and none of them would fit the feeling.

And what made things worse was I remembered those 47 poor devils who were suffocated to death in August in the Argonaut mine in California. Pure damned cussedness and delay and carelessness that was. Forty-seven men bulkheaded themselves in a cross-cut on the 4,350 ft. level, having no means of escape and 47 brave men died like rats in a trap. I'll tell you the story one day.

The Argonaut Mine disaster occurred in 1922, so the date for this article seems reasonably firm, even though I couldn't directly confirm it. Still, the theory that "pure D" comes from "pure damn[ed]" has two difficulties: (1) Aside from the 1923 instance cited here, I haven't found any instances of "pure damn[ed]" until long after "pure D" became established as a Southern regionalism; and (2) in James Street's usage in 1941 and in Mack Hughes's usage (once out of nine times) at an unknown date before 1989, "pure D" or "pure-dee" has a positive edge, very different from the sense of "unmitigated" attributed to it in Brunner's glossary.

Robert Hendrickson, The Facts on File Dictionary of American Regionalisms (2000) identifies the core sense of the term as not "unmitigated" but "unadulterated":

pure dee luck Pure unadulterated luck. "My second was a heart shot and pure dee luck. I'd tried for the heart, of course, but with him running like that it was a chancey thing.” (Louis L'Amour, Bendigo Shafter, 1979)

"Unadulterated" may be the most accurate synonym for "pure D," since that meaning makes sense in expressions as varied as "pure dee heaven," "pure-dee hell," "pure dee fact," and "pure dee water." How "pure damned" might have arisen as a synonym for "unadulterated" is unclear to me. At the same time, though, Jonathon Green, Cassell's Dictionary of Slang (2005) gives no rationale for the extension of "pure dee" to the term "pure idee":

pure-d adj. (also pure dee, pure idee) [1950s+] (US) complete, absolute, utter. {PURE adv. + ? D adj.}

Much remains to be explained.

"Pardie" and "Perdie" are alternatives to "Par Dieu"="By God". Throw in a Cajun or Texan accent and you get "pure-d".

When we were kids, if something was crap we'd say it was Pure-d. When something was good it was Grade-A. "After his crash, his grade-a bike became pure-d."

I was in an Air Force family stationed at Webb AFB just outside Big Spring in West Texas, in the 1960s, and attended my last 2 years of high school at Big Spring High School. I heard "pure-d" in a lot of conversations, and still use it in conversation when I want to emphasize the absoluteness or purity of something. I've read that it is used as an 'intensifier', which is a good definition. I even used it unconsciously in a poem in a small book I published. I seldom hear it, and usually it comes from someone with a Texas background. It's a little like another rare word, larrapin', which I picked up further north in Amarillo, TX, although it's found a lot of places in the American South, and means "delicious", primarily of food.