A new and improved overhead door apparatus is provided for a structure, such as an enclosed trailer or enclosed truck body, and includes a pair of guide channel assemblies connected to a pair of sidewalls of the structure a predetermined distance from the floor of the structure. A pair of central pivot assemblies are connected to the pair of sidewalls. The central pivot assemblies are located on the pair of sidewalls at locations between the pair of guide channel assemblies and the floor. A rigid unitary door panel assembly which contains an interior X-frame assembly includes a pair of top corners, a pair of bottom corners, and a pair of sides separating the pair of top corners from the pair of bottom corners. The pair of top corners of the door panel assembly includes a pair of roller assemblies adapted to roll along the pair of guide channel assemblies. A pair of first extensible and retractable assemblies are pivotally connected between the pair of top corners of the door panel assembly and the pair of central pivot assemblies.