In related news, the dance scene with the dividing gym floor with the pool underneath was filmed at Beverly Hills High School. My ex-wife's step-father attended school at Beverly Hills High School, played in that gym, and danced in that pool....for what it's worth.
The side of the box reads, "To help celebrate his brother's graduation, George Bailey wanders over to the high school dance. Before he knows it, he's kicking up a storm in a Charleston contest with his future wife, Mary Hatch. The crowd gasps as they sway. Not because they are great dancers, but because they're dancing on a gym floor that's slowly opening onto the edge of a swimming pool. They fall headlong into the pool and are soon joined by the rest of the reveling crowd."