Sometime in the 1980s, a comedian joked about the lost paintings of Norman Rockwell—-one was titled “Boy Caught Masturbating.” Yet, since the exhibition “Telling Stories: Norman Rockwell from the Collections of George Lucas and Steven Spielberg” opened at the Smithsonian American Art Museum in July, it seems like it’s been critics who’ve been caught with their pants down, choosing sides and stroking the same arguments that have been tossed off since Greenberg drew the lines between the avant-garde and kitsch. What they ignored in their debate is the fact that this show is not about asserting Rockwell’s greatness as a fine artist. The exhibition is about outlining the influence of Rockwell on one consistently good moviemaker, and and a guy who jumped the shark in a galaxy far, far away. Fortunately, SAAM will show its hand tonight when it screens George Lucas’ American Graffiti (the only one of the six full-length feature films Lucas directed that looks anything like the earth we know).

To get to the influence, let’s first address the 400-pound gorilla. There is no denying that Rockwell is a great draftsman, as well as an inviting and sentimental one. That was his job as an illustrator selling lamps, and the Boy Scouts of America, and The Saturday Evening Post. To be clear, when interviewed, Rockwell classified himself as an illustrator, though he was trained in and worked in oils. So, let’s put aside the argument of whether Rockwell is museum-worthy. He is, and deserves a place in a museum of illustration somewhere between the swash-type advertisements for Chesterfields, and the pull-no-punches Esquire covers of George Lois.

For as inviting and sentimental as Rockwell was, so too are many of the films of Spielberg and Lucas—-though they don’t have the wall-to-wall sentimentality of a Rockwell illustration. For instance, a touching scene in Jaws shows the young boy mirroring his father at the dinner table. Or the amusing moment when three men get drunk and compare scars on the boat. Compared to today’s summer blockbusters with their overblown symphonic music and quick-cut action sequences, Jaws is relatively quiet. Some of its scenes could be lost Rockwells: “Man Learning to Tie Knots,” or “Proud Fishermen Land Big Catch.” Sometimes the sentimentality is a touch more in-tune with contemporary culture, as in Raiders of the Lost Ark when the young female student in Dr. Jones’ class slowly blinks, revealing the words “Love You.” It’s the perfect counter to Rockwell’s “Happy Birthday Mrs. Jones.” That’s the rare example of when a direct comparisoncan be made between the movies of Spielberg and the illustrations of Rockwell. More often Rockwell is a garnish, a device to slow the movie up a bit and break any tension.

With Lucas, the influence of Rockwell is a tougher sell. Most of the movies he directed take place on spaceships, and have more of a relationship with the camp of early cinema serials. If there’s an overt Rockwell-Lucas link in Star Wars, it might be the clumsiness of Anakin Skywalker as he backs a starfighter out of a hanger in The Phantom Menace—-all Jake Lloyd needed to do was widen his eyes, purse his lips, and put a hand to his mouth as he looked at the camera. More often it’s a masked reference, literally, with a clumsy Ewok or droid. American Graffiti, however, is ripe with Rockwellian Americana clichés, and George Lucas does not hesitate to flaunt the influence. However, Lucas does it with slightly cynical differences: The high-school sweet hearts break up; the dork gets drunk and lucky and loses a car; Richard Dreyfuss stalks a woman in a white T-bird and gets initiated into a gang; the grease monkey gets stuck babysitting; and Harrison Ford gets the day off from carpentry to cruise around town in a white Stetson hat. Throughout all the sentimentality, there is the slightest awareness of Vietnam. And though they’re upbeat, the characters don’t all have happy endings.

Perhaps that is the back-story for Rockwell’s paintings; not all of his paintings have happy endings, either. Though a young man sits at a typewriter, dreaming of Daniel Boone, we’ll never know if he wrote the best seller. Though the young decorated soldier home from WWII is pleased as punch, he’ll have nightmares of killing Krauts. Though the rookie enters the Red Sox locker room, he might not stick around the big leagues for long. Though the family of five bursts through the front door, with the youngest shouting Merry Christmas, they might all only get socks as gift. Oh, and lest we  forget: The oldest son of that family got caught using the sock incorrectly.

American Graffiti plays tonight at 6:30 p.m. in the Smithsonian American Art Museum’s McEvoy Auditorium, lower level. Admission is free.