How did the 1916 New York City zoning law influence the stepped shape of skyscrapers?

The 1916 New York City zoning ordinance was a landmark piece of legislation designed to regulate urban density and ensure that light and air could reach the streets below. By mandating that buildings incorporate setbacks—receding portions of the structure as it increased in height—the law fundamentally altered the silhouette of future skyscrapers.1

This requirement for setbacks directly influenced the iconic "stepped" or ziggurat shape of many famous buildings, such as the Chrysler Building and the Empire State Building. Beyond the legal mandate, this design also provided an economic advantage: as the building rose and the floor plates narrowed, the resulting configuration allowed for efficient, rentable peripheral office space in the upper levels where elevator capacity naturally diminished. This combination of regulatory necessity and functional planning helped define the soaring, jagged aesthetic of the early 20th-century American skyline.12