Due to the military-looking people in the background, I initially thought it might be from the Hollywood Victory Committee meeting shortly after Pearl Harbor. Amy Jeanne, whom herself wasn't sure, thought that was a possibility.
But another look at the photo shows an airplane is in the background (which would scuttle the Victory Committee angle), and someone suggested that it might be Clark and Carole arriving in Atlanta for the "Gone With The Wind" premiere. I'm leaning in that direction, but not 100% certain. Can anyone confirm this?