July 2, 1939: NBC showed The Aldrich Family.
The Aldrich Family was a popular teenage sitcom that focused on the adventures of Henry Aldrich, the Aldrich Family's son. It was well-remembered for its introduction, with Henry's mom shouting, "Hen-reeeeee! Hen-ree Al-drich!" The show lasted until 1953.
Enjoy this later broadcast "Selling Christmas Cards" from 1942: