Traditional zoning first took hold in the early 20th century with a clearly logical intent, as the word implies: to establish and keep apart discretely delineated areas of land use within counties and municipalities. Single-purpose zones ensured separation of incompatible uses such as dwellings and factories.
Zoning’s aspirations were essentially utilitarian, not aesthetic. Zoning rarely addressed or set guidelines for urban design and architectural quality. Rather, it protected public health and safeguarded property values by preventing negative effects attributable to laissez-faire real estate development.
Within each distinct zone, laws typically allowed only certain types of use, such as detached one-family homes or commercial buildings. Zoning also specified building densities and height limits, minimum yard and setback dimensions and minimum parking space requirements. Those zoning criteria have persisted.
Fortunately, mixed-use development is at last beginning to supersede single-use development, especially to make new or revitalized areas more walkable. No one proposes building factories in the middle of residential neighborhoods. But today’s master plans, despite current zoning, increasingly envision communities that encompass not only diverse housing types but also retail shops and stores, restaurants, offices, cultural destinations and recreational facilities.
Prescribed maximum densities — dwelling units per acre or total building square footage — allowed under existing zoning ordinances are becoming negotiable and more flexible. Density can increase for several reasons, frequently not because of zoning but because of contracts or covenants signed by property owners, tenants, governments and sometimes citizen organizations.
Governments can grant a developer additional density rights in return for public improvements or amenities not required by zoning. Benefits offered by developers may include additional parkland, construction of a community facility, space in buildings for nonprofit or cultural entities, off-site street or utility improvements or a specified percentage of affordable housing units in addition to market-rate units.
Linked to density are increased building heights in appropriate locations and on sites that make urban design and architectural sense. Places exist in cities, towns and suburbs where higher buildings can become iconic landmarks, better enclose civic spaces, take advantage of favorable views and topography and contribute to activating streetscapes. Owing to greater tax receipts, higher buildings and denser development also yield fiscal benefits.