It’s impossible to look at the green dress Scarlett O’Hara made from curtains in the movie Gone With the Wind without thinking of the Carol Burnett parody, complete with curtain rod.

“After that skit, the curtain dress became the Gone With the Wind dress,” says Steve Wilson, curator of “The Making of Gone With the Wind,” an exhibition that opened Tuesday at the University of Texas’s Harry Ransom Center marking the 75th anniversary of the film based on Margaret Mitchell’s novel.

Fans will doubtless flock to Austin to see that dress and two others that adorned Vivien Leigh. These costumes do what costumes do—dress up the exhibition—but the true stars of this show are the memos, such as producer David O. Selznick’s letter assuring Ed Sullivan that “Vivien Leigh is by no means cast as Scarlett” (although she had been) and the Ku Klux Klan Grand Dragon of California’s offer to serve as a technical adviser (turned down), along with reams of letters from fans begging the movie to get Southern accents right (it pretty much did, although Clark Gable steadfastly refused to do one).

Though it seems exhaustive—and a bit exhausting, given that many of the missives are in 10- or 12-point, single-spaced, blurry manual type—the collection of memos actually represents just the tip of a 5,000-box iceberg of papers that Selznick’s sons bequeathed to UT in 1980. The man wrote a lot of memos, many Benzedrine-fueled. There’s a memo about that, too, in which Selznick asks that someone look into claims that the amphetamine might be bad for you: “I am practically living on the stuff and would prefer that I do not explode for a couple of years or at least until Gone with the Wind is finished.”

Not everybody is a fan of this movie, of course, and the exhibition includes protest letters, correspondence with the NAACP, and back-and-forth between the producer and production staff over the use of the N-word (it was excised in favor of “darkie,” recommended by the censoring Motion Picture Production Code, better known as the Hays Office), as well as notes about the decision to delete any reference to the Klan, despite the Grand Dragon’s assertion that if the KKK were “distorted or deleted, the South would be insulted.”

Also, the university is offering a Sept. 17-20 symposium, “Cultural Life During Wartime, 1861-1865” to examine the historical context of the film. With discussions of songs, images, and other cultural aspects of the times, the symposium seems designed at least in part to tamp down criticism of its celebration of a movie that glorified the plantation period as a sweet, wonderful time when all Southern white people owned happy slaves.

Regardless, the place of Gone With the Wind in film history is irrefutable. Its domestic gross of $1.6 billion is still an inflation-adjusted record, and it won ten 1940 Academy Awards, including Best Picture, in what was probably the most competitive Oscar year ever. What the Ransom exhibition celebrates with costumes, story boards, screen tests, photos, and those delightful memos is the enormous effort it took to turn Mitchell’s 1,000-page book into a (somewhat) manageable, nearly four-hour movie. The project was a beast.

The exhibit chronicles the casting of Scarlett as a monumental undertaking. Early favorites were Miriam Hopkins and Joan Crawford. Virtually every Hollywood actress wanted the part, including Bette Davis, whom Selznick vetoed because she’d recently starred in the much-too-similar “Jezebel.” Tallulah Bankhead campaigned hard for the role, and Selznick had to deal with gossip columns proclaiming he’d chosen Katharine Hepburn, when his memos show he considered her “all wrong for it.”

Given the success of the book worldwide, Selznick thought an unknown might be used, and a nationwide search was launched. Drama schools were visited; members of the public were allowed to nominate themselves. None showed promise. Paulette Goddard emerged as a favorite for Scarlett, right up until Selznick saw and heard Leigh.

As for Rhett Butler, public opinion glommed onto Clark Gable from the start, although Selznick’s memo indicates he would’ve been “equally happy” with Gary Cooper. The trouble with Gable was that he was under contract to MGM.

“He did not want to play the part,” Wilson says. “He felt that the public had an image of Rhett Butler, and he was afraid he wouldn’t be able to live up to it.” Eventually, Gable relented, and MGM let him.

For Mammy, Selznick first favored Louise Beavers (Imitation of Life), considered and rejected Eleanor Roosevelt’s maid, then wound up choosing Hattie McDaniel, whose performance earned an Oscar.

The Scarlett-suiting Tarleton Twins presented a problem, because nobody could find twins who could act. Non-twins were cast and paid extra to dye their hair red for the first day’s shoot, which Selznick decried as making them look like a couple of Harpo Marxes.

Selznick was appropriately fretful from the start about length. The movie started shooting with George Cukor as director, but Selznick thought his pace was too slow. Worrying that Cukor “would take a four-hour script and make a six-hour movie,” he let him go in favor of Victor Fleming, who would later briefly leave the picture after a collapse (Sam Wood stepped in) but return to finish it.

Similarly, the writing was a Herculean task. The main writer was Sidney Howard, but Selznick hired numerous others, including F. Scott Fitzgerald and Ben Hecht, to tighten and refine. Early on, a six-page Selznick memo to Howard about the scriptwriter’s initial treatment urges that Howard stick to the book, not try to tone down Rhett Butler’s “boorishness” and (thank goodness) avoid creating a dream sequence for Scarlett. The production then faced an even longer missive from the Hays Office demanding that there be no suggestion of rape anywhere, that there be no “undue exposure” of the women’s bodies, that Butler consort Belle not be portrayed as being employed by a brothel but from “a drinking or gambling establishment,” that wounded soldiers not be shown as gruesomely suffering, and that, above all, Melanie Wilkes’ childbirth not to be portrayed as painful in any way.

The Hays Office didn’t get its way about everything, of course. One key demand was that “As God is my witness” be excised from Scarlett’s radish speech, but it stayed and is one of the film’s most memorable lines.

Be sure not to miss Selznick’s over-the-moon missive to major investor John Whitney on the day an exhausted Leigh finished her last shot. “Sound the siren. Scarlett O’Hara complete her performance at noon today,” it begins, ending: “Please tell Margaret Mitchell what she may do to herself.”

This memo alone merits a trip to the UT campus for the Ransom exhibition—which is free, by the way, and runs through Jan. 4.

Oh, and the Carol Burnett parody version of the Scarlett O’Hara green curtain dress, designed by Bob Mackie? It’s owned by the Smithsonian Institution.

“We’d would’ve liked to have had it,” Wilson says wistfully.

Want more GWTW?

• On Sept. 30, Warner Bros. Home Entertainment will release the “Gone with the Wind 75th Anniversary Ultimate Collector’s Edition” on Blu-ray and Digital HD with Ultra-Violet.

• Marietta, Georgia, has a Gone with the Wind Trail that includes a museum and Mitchell’s birthplace in Atlanta (gwtwtrail.com).

• Expect a heavy rotation this fall of Gone With the Wind on Turner Classic Movies, which is premier sponsor of the Ransom’s exhibition.