Cities need to be flexible and allow for changing needs, whether in roads, public spaces or buildings. For example, cities could provide more housing by converting unused offices or hotels. But several factors prevent this. Rigid and often outdated zoning codes block adaptation to new uses—New York City’s original 1916 zoning codes ran about 14 pages, and today, it’s at 3,500. Also, political and cultural opposition to change has arisen that gives neighbors the ability to veto projects. And a lack of housing is lucrative for individuals and cities because home prices and thus tax collections increase.