Both. In order to encourage existing building owners to keep their existing height, they were able to sell their air rights, which then made it possible to buil

Both. In order to encourage existing building owners to keep their existing height, they were able to sell their air rights, which then made it possible to build tall skinny buildings. https://www.theguardian.com/cities/2019/feb/05/super-tall-super-skinny-super-expensive-the-pencil-towers-of-new-yorks-super-rich https://www.theguardian.com/cities/2019/feb/05/super-tall-su...