An improved cargo dolly has at least two top rail assemblies and a frame with an inner rail having mounting brackets for receiving the top rail assemblies. Each top rail assembly spans the width of the frame but not the length of the frame and can move between an attached state and an unattached state by actuating fasteners that pass through the top rail assembly to its respective mounting brackets on the frame. The movement between the attached and unattached states occurs independently of an attached or unattached state of the other top rail assembly.