WAMEGO, Kan. — When “The Wizard of Oz” first hit theaters in August 1939, flying monkeys were the least of America’s worries.

The Depression, already almost a decade long, continued to grind away, and Germany stood on the verge of invading Poland, igniting a global conflagration that would envelop the United States just two years later.

Moviegoers needed escape. And along came Judy Garland’s Dorothy Gale, a Kansas farm girl whose ruby slippers stepped out of the dreary present and into a Technicolor future, a magical Oz populated by talking scarecrows, Munchkins, bubble-riding witches and a con man of a wizard who showed that all we ever needed was within ourselves.

Seventy years after its first screening, “The Wizard of Oz” returned to theaters nationwide Wednesday for one night as Warner Bros. unveiled a technologically updated and improved version ahead of its release on Blu-ray Hi-Def.

“A film like this, which is so unlike any other motion picture and so beloved by the public all over the world, it deserves to be seen in the best possible light,” said George Feltenstein, senior vice president of WB’s theatrical catalog marketing.

The world is no less scary than it was 70 years ago, and the fantasy genre has tilted ever darker through the years — nightmarish images from “Pan’s Labyrinth” or the “Harry Potter” and “The Lord of the Rings” films can make a wicked witch’s castle look downright homey.

But despite its campy tone and crude special effects, “The Wizard of Oz” has retained its popularity.

Between regular television airings and the many fan conventions and festivals around the country, there’s no shortage of Oz. The Oz Museum in tiny Wamego, west of Topeka, draws tens of thousands of visitors to view some of 24,000 pieces of Oz memorabilia.

“I think I first saw the movie when I was 4,” said Shelley O’Neil, 45, of Greeley, Colo., during a recent visit to the museum. “I was sitting there just mesmerized until the monkeys came on and apparently I just started screaming. My mom had to come save me. I think we watched it every year.”

For many fans, the Sept. 23 showing will be the first chance they’ve had to see “The Wizard of Oz” on the big screen since its last national theatrical release in 1955. And even frequent viewers will be in for a surprise, Feltenstein said, as the new version, digitally sharpened and brightened, provides textures and details that were invisible in past prints.

“I’ve seen it so many times on television but when I saw (the new version) it was like seeing a brand new film,” said Robert Osborne, film historian and host of Turner Classic Movies, who will introduce the film before its showing.

The movie was based on L. Frank Baum’s 1900 children’s book, “The Wonderful Wizard of Oz,” which itself amassed quite a following. Baum wrote 13 sequels and authors approved by his estate later penned 26 more.

Evan I. Schwartz, author of “Finding Oz: How L. Frank Baum Discovered the Great American Story,” said Baum set out to create a fairy tale that used the traditional “quest” story to teach lessons about wisdom, compassion and courage but eschewed the knights and dragons of European folklore. Instead, he used American images, such as the scarecrow and the tin man, inspired by Baum’s time in the oil industry. He also used the hidden wizard pulling the strings to touch on the nation’s naivete.

“We’re an inventive people but we’re also a very gullible people,” Schwartz said, noting that headline writers regularly referred to disgraced financier Bernard Madoff as “the man behind the curtain.” “I think Frank Baum had the ability to hear what people were thinking and it taps into this collective unconscious of America and it’s still there.”

Oz was turned into a successful Broadway musical and three silent films before Metro-Goldwyn-Mayer began making the definitive version in 1938.

The movie was groundbreaking for its use of the then-new Technicolor, its costumes and special effects, as well as its songs, including “Somewhere Over the Rainbow.”

Osborne said one of the miracles of the film for him is all the ways it could have gone wrong. Producers originally wanted Shirley Temple as Dorothy and comedian W.C. Fields as the Wizard and considered using a real lion instead of a costumed actor. They also envisioned the Wicked Witch of the West as beautiful and cast the glamorous Gale Sondergaard before switching to Margaret Hamilton when others pushed for a disfigured, obviously evil villain.

“You wonder, ’Would it have been the same movie?” Osborne said. “I’m not sure it would be. I’m not saying it wouldn’t have been good but it might not have had the timelessness that it has because of the people involved.”

Upon release, it was considered a moderate success, largely because it had cost so much to make. Only after its re-releases in 1947 and 1955 did it start turning a profit and finding wider audiences.

The film’s imprint continues to be felt as Oz references, homage and parodies pop up regularly in movies, TV shows, literature and music, ranging from the SyFy Channel’s “Tin Man” series to the Broadway plays “The Wiz” and “Wicked.” It also has likely inspired many of the fantastical visions generated from Hollywood over the last 30 years.

“There’s no question that Steven Spielberg, George Lucas, Peter Jackson, almost any influential contemporary filmmaker you could name grew up on ’The Wizard of Oz,”’ said film critic and author Leonard Maltin. “Its influence cannot be denied or even underestimated.”

Back in Wamego, the locals are planning this year’s OZtoberFEST, an annual festival held on the first weekend of October that combines country fare with Oz adulation, including a stage performance of the story and appearances by relatives of Baum and some of the surviving Munchkin actors.

This year’s festival will coincide with the annual convention of the International Wizard of Oz Club, where thousands of fans digest the latest in fan-created film, fiction and art based on the story and movie.

“Oz is a country where everybody fits in, where everyone is welcome, where young people can accomplish things that only adults can accomplish in the outside world,” said Jane Albright of Kansas City, Mo., a club member with more than 6,000 items in her Oz collection. “When something is that compelling to you when you’re young it can really capture your imagination.”