What is Zoning?
Zoning is a set of laws that govern how large buildings can be, how they are built and what they are used for.
Every square inch of New York City that is not a street, a park on under water is zoned, meaning there’s a law governing what can be built there.
Zones in New York City are generally divided into three categories: residential (R), commercial (C) and manufacturing (M). There are other MX districts that combine some uses, especially manufacturing and residential. There are also “commercial overlays” that allow a mix of stores and homes.
Within each broad category are a set of sub-designations, usually numerical. These restrict the type of usage (for instance, M3 districts cater to heavy industry but M1 districts do not) but also address how big a new building can be.
The size regulations address how bulky a building can be, meaning how much of its lot it can take up. They also regulate how dense, or tall, it is. A key element in those regulations is Floor Area Ratio, which relates the height of a building to the width of its base. The regulations also affect certain design considerations, like setbacks (when a building has a narrower base at an upper floor).
New York City was the first U.S. municipality to pass a citywide zoning code, back in 1916. The Department of City Planning, which administers the Zoning Resolution, offers a detailed online guide to zoning, including a glossary and a guide to the different zoning districts.