It’s the hundredth anniversary of New York’s first real zoning law and there have been some good write-ups, for example in the Times and on Curbed. David Dunlap’s article in the Times is absolutely right that the typical story of the zoning law is oversimplified, but I want to take that idea in a different direction. As he said, the Equitable Building wasn’t the cause of the zoning law but it’s not a bad example of what can happen without zoning. Here’s Pine Street, immediately south of Equitable, looking up:
Equitable goes up 40 stories without a setback, more than twice what would have been allowed using the 1916 law’s geometry rules of setbacks required after a height that was a (variable by location) multiple of the adjacent street width. But there was an important loophole: once the setbacks had reduced the size of the floor plan to one quarter of the lot size, the building was allowed to go up forever. If you look at the very tall towers of the 1916 law era (in other words, from the late 1910s until 1960), you see buildings with big bases, a bunch of setbacks, and then a tall shaft of typical floors that are one-quarter of the lot size in area, and then usually some more setbacks at the top. This pattern shows up, for example, at the Empire State, at Chrysler, at 40 Wall Street, at 70 Pine Street, at 500 Fifth Avenue, and so on.
The setback form is traditionally traced to Eliel Saarinen’s 1922 second-place entry in the architectural competition for the Tribune Building in Chicago, although there were similar ideas already floating around. For example, the Singer Building was constructed in stages in a somewhat ungainly form that had a broad mid-rise base with a slender tower.
But – and this is a big problem with the zoning-led-to-setbacks idea – nothing in the zoning law forced people to build setbacks or slender towers. The zoning law could have led to the design, construction, and real-estate communities building a city of blocky buildings with uniform cornice heights, looking like a taller Paris. That cornice height would have been determined by the height where setbacks were required. This is not idle speculation, as it is pretty much what happened on West End Avenue.
Instead, people used setbacks and the one-quarter loophole to building taller. The best answer to “why” is that the pressure to build tall (i.e., dense) already existed, for social, economic, and business reasons, and the zoning law simply determined how that density was shaped.
On the other hand, a lot of people including me find the aesthetics of the setback skyscrapers appealing. So maybe examining why too closely is pointless.