Zoning

In urban planning, zoning is a method in which a municipality or other tier of government divides land into land-use and building "zones", each of which has a set of regulations for new development that differs from other zones. Zones may be defined for a single use (e.g. residential, industrial), they may combine several compatible activities by use, or in the case of form-based zoning, the differing regulations may govern the density, size and shape of allowed buildings whatever their use. The planning rules for each zone determine whether planning permission for a given development may be granted. Zoning may specify a variety of outright and conditional uses of land. It may indicate the size and dimensions of lots that land may be subdivided into, or the form and scale of buildings. These guidelines are set in order to guide urban growth and development.

Zoning is the most common regulatory urban planning method used by local governments in developed countries. Exceptions include the United Kingdom and the city of Houston, Texas.

Most zoning systems have a procedure for granting variances (exceptions to the zoning rules), usually because of some perceived hardship caused by the particular nature of the property in question.

The origins of zoning districts can be traced back to antiquity. The ancient walled city was the predecessor for classifying and regulating land, based on use. Outside the city walls were the undesirable functions, which were usually based on noise and smell. The space between the walls is where unsanitary and dangerous activities occurred such as butchering, waste disposal, and brick-firing. Within the walls were civic and religious places, and where the majority of people lived.

Beyond distinguishing between urban and non-urban land, most ancient cities further classified land types and uses inside their walls. This was practiced in many regions of the world – for example, in China during the Zhou Dynasty (1046 – 256 BC), in India during the Vedic Era (1500 – 500 BC), and in the military camps that spread throughout the Roman Empire (31 BC – 476 AD).

Throughout the Age of Enlightenment and Industrial Revolution, cultural and socio-economic shifts led to the rapid increase in the enforcement and invention of urban regulations. The shifts were informed by a new scientific rationality, the advent of mass production and complex manufacturing, and the subsequent onset of urbanisation. Industry leaving the home reshaped modern cities. The definition of home was tied to the definition of economy, which caused a much greater mixing of uses within the residential quarters of cities.

Separation between uses is a feature of many planned cities designed before the advent of zoning. A notable example is Adelaide in South Australia, whose city centre, along with the suburb of North Adelaide, is surrounded on all sides by a park, the Adelaide Park Lands. The park was designed by Colonel William Light in 1836 in order to physically separate the city centre from its suburbs. Low density residential areas surround the park, providing a pleasant walk between work in the city within and the family homes outside.

Sir Ebenezer Howard, founder of the garden city movement, cited Adelaide as an example of how green open space could be used to prevent cities from expanding beyond their boundaries and coalescing. His design for an ideal city, published in his 1902 book Garden Cities of To-morrow, envisaged separate concentric rings of public buildings, parks, retail space, residential areas and industrial areas, all surrounded by open space and farmland. All retail activity was to be conducted within a single glass-roofed building, an early concept for the modern shopping centre inspired by the Crystal Palace.