Abstract: An expandable-retractable portable structure is provided which is capable of being transported on public highways in its retracted position. The structure has a stationary portion and a movable portion, wherein the movable portion pivotally encloses the stationary portion of the structure in the retracted configuration of the structure. The movable portion of the structure carries a winch which when activated causes the movable portion to move from the expanded configuration to a retracted configuration by pivotally enclosing the stationary portion of the structure. The winch is reversed in direction to rotate the movable portion from the retracted to its expanded configuration wherein maximum interior space is available within the structure for use.