What was in the Los Angeles water supply in 1939?

That year, 70 years ago, is widely considered to be the greatest year ever for movies.

Reading the list of Best Picture Oscar nominees that year is a murderer's row of great films: "Gone With the Wind" (which won), "Dark Victory," "Goodbye, Mr. Chips," "Love Affair," "Mr. Smith Goes to Washington," "Ninotchka," "Of Mice and Men," "Stagecoach," "The Wizard of Oz" and "Wuthering Heights."

(Yes, the Academy Awards nominated 10 movies for Best Picture through the '30s and up to 1943 -- a tradition the Academy is reviving with next year's Oscars, to allow more contenders for the top prize.)

Five of those nominated movies ("Gone With the Wind," "Mr. Smith Goes to Washington," "Stagecoach," "The Wizard of Oz" and "Wuthering Heights") appeared on the American Film Institute's 2007 list of the greatest American movies of all time. Some also represent the best of their genres: "The Wizard of Oz" remains one of the greatest children's fantasies ever, "Mr. Smith" ranks as one of the top movies about politics, while "Stagecoach" still stands out as one of the best Westerns. And so on, down the line.

And those 10 aren't the only well-known movies made in 1939:

» Judy Garland and Mickey Rooney had one of their best musical outings in "Babes in Arms."

» Gary Cooper shined in the French Foreign Legion in "Beau Geste."

» Cary Grant swashbuckled across India in "Gunga Din."

» "The Little Princess" was possibly Shirley Temple's best movie.

» Charles Laughton donned uncomfortable prosthetics to play Quasimodo in "The Hunchback of Notre Dame."

» U.S. moviegoers were introduced to the Swedish discovery Ingrid Bergman in "Intermezzo."

» And "The Women" united several of the era's biggest leading ladies -- Norma Shearer, Joan Crawford and Rosalind Russell -- for some major back-biting (which didn't work nearly so well in last year's remake, starring Meg Ryan and Annette Bening).

When people look at today's movies and say, "They don't make 'em like they used to," 1939 is the year they used to make 'em like that.

But why?

Cinema technology had improved, for one thing. A dozen years after talkies were introduced, Hollywood studios had finally figured out how to capture visuals and sound simultaneously without looking like a recorded stage play. Cameras and film stock also improved, and the advances in the uses of Technicolor -- deployed brilliantly in "Gone With the Wind" and "The Wizard of Oz" -- were showing the movie audience the joys of living color.

In 1939, the country was also beginning to emerge from the throes of the Depression, and Hollywood was free to be more lavish with its budgets. At the same time, Hollywood was benefitting from the talent of European writers and directors (such as Billy Wilder, who co-wrote "Ninotchka") escaping the rise of Hitler's Germany.

Not every movie made in 1939 was a classic, of course. Selectivity is one benefit of memory, and the mediocre movies of 1939 have long ago faded into obscurity. The same will happen to the not-so-good movies of 2009. The question is: Will today's Hollywood leave behind as many gems as that magical era 70 years ago did? We should be so lucky.

Sean P. Means writes the Culture Vulture in daily blog form at blogs.sltrib.com/vulture