Following the opening of the blocky and (for the time) astronomically tall 41-story Equitable Building in 1915, New York City's zoning laws were changed in 1916, requiring setbacks on the upper floors of tall buildings to provide more light at street level and reduce shadows. This seemingly minor change would have a dramatic architectural impact on the appearance of the NYC skyline up through the middle of the century. Setbacks also fit seamlessly into the vertical orientation of Art Deco and the "Wedding Cake" style would become a defining characteristic of Art Deco architecture. Completing the phallic symbolism, many Art Deco buildings have rounded cupolas.
This stairstep design was also incorporated into other vertically-oriented structures.
Next: Sans Serif Fonts