Disclosed herein is a modular deck system that utilizes a combination of a movable platform having a plurality of vertical posts with engagement members. Decks, filled with freight, can be placed onto the vertical posts at various heights at different sections of the movable platform using a conveyance vehicle. Further, the height of the vertical posts can be extended using an extension post for securing tall cargo. The decks can also be locked to the vertical posts to prevent dislodgement of the deck during transport of the movable platform.