Steel Skeleton

Before elevators, buildings were pretty much limited to six stories. It would have been useless to add more stories as people could not be expected to climb any higher. The elevator enabled an increase in building height to about eleven stories. Any additional stories and the walls of the lower floors would have to be so massively expanded and stabilized that any gain in space and rent would be negligible. This dilemma was solved at the beginning of the 1880s, in the wake of the great Chicago fire, by the development of steel frame construction, which greatly increased the potential number of floors by transferring the load-bearing function of masonry walls to a steel skeleton.