Zoning regulations
Legal restrictions which were intended in the first place to relieve street congestion by regulating the height of buildings. The New York Zoning Act of 1916, the first American act of the kind and the model for most later ones, determined the permissible height of walls next to the street by two factors, the type of district or zone and the width of the street. Additional stories above this had to be set back behind a line drawn from the center of the street through a point at the top of the front plane of the street wall, except that upon one quarter of the total lot area the building could rise to any height. (Whiffen, 1969, 1996)