Abstract: The display sign assembly comprises a trailer having a flatbed thereon, sign frame supports mounted upon the flatbed, a sign frame formed into a quadrilateral configuration and having a plurality of channel members each having a U-shaped cross-section with the open sides of the channel members directed inwardly of the quadrilateral configuration, and a wall having edges which are received in the open sides of the channel members and which are sealed to the channel members so that moisture cannot seep between the wall and the channel members. The sign frame also includes a pair of reinforcement channel members fixedly attached back-to-back to one another and traversing through the quadrilateral configuration and attached to at least two of the other channel members which form the quadrilateral configuration to stabilize the wall and essentially prevent the wall from wobbling back and forth as the trailer is moved upon a road.