Abstract: The techniques described herein relate to an expansion mechanism for an article of luggage. The article of luggage may include a rear housing portion defining a rear storage area that can be increased when the expansion mechanism is in an expanded state. A gusset may couple portions of the rear housing portion together and can be slack or taut. A first and second piece of the expansion mechanism may be mounted to the portions of the rear housing portion, respectively. When the pieces of the expansion mechanism separate in an expanded state, the gusset may also expand to a taut state. The rear storage area can be increased when the expansion mechanism is in an expanded state. The expansion mechanism may freely slide from a closed state to an open or expanded state.