Abstract: An articulated cover assembly for covering the top opening of trailers and the like having two covers which are movable between a position covering at least a portion of the top opening of a trailer and a position substantially removed from the trailer. The covers travel upon a track such that they may be rolled between the opened and closed positions. The covers are preferably comprised of a rigid material, such as plastic or fiberglass. A tongue and groove interface intermediate the two covers provides a seal therebetween. The track may be comprised of two track sections: a horizontal first track section comprised of two elongate rails positioned upon opposite sides of the trailer and extending horizontally therealong, and a second track section comprised of two elongate rails positioned at either end of the trailer and sloping downward from approximately the height of the first track section.