An elevator system which utilizes a plurality of independently moving cabs and counterweights in each elevator shaft. Each cab is connected to one or more spatially separated counterweights at different counterweight connection points. The connection points are horizontally shifted on different cabs in order to prevent interference between cabs, cables, pulleys and counterweights. The top cab may have one counterweight cable and may be connected to one or more counterweights by connection points on the roof of the cab. The cabs are mounted on two opposing vertical guide rails, and each guide rail is mounted at the center of one side of the elevator shaft. The system includes a motor attached to each of the cabs by one or more lift cables to facilitate the independent movement of all cabs. Existing buildings can also be retrofit for compatibility with the present invention.