Site, function and land use

An urban place is a settlement where population is concentrated, the environment is built up and activities are predominantly non-agricultural. Countries classify settlements as urban using different criteria, so take care when making international comparisons.

The physical characteristics of the land on which a settlement is built are its Site. Relief, water supply, drainage and ground conditions shape where building starts and how the settlement expands. Construction may be easier on a flat river terrace; steep slopes or a floodplain can restrict it. A harbour site can encourage a port to develop.

A settlement's Function is the role it performs. Urban functions include administration and manufacturing, as well as trade, transport, education and tourism. Large cities usually perform several functions. Smaller towns may rely more heavily on one. As industries decline or new activities develop, these functions can change.

Land use describes what land is used for. Residential and retail uses compete for urban space alongside commercial, industrial, recreational and transport uses. Where these uses occur reflects the city's site, functions and development history. In a port city, for example, warehouses and industry may sit beside the waterfront.

Settlement hierarchy and megacities

A settlement hierarchy ranks settlements using characteristics such as population size and the range and importance of their functions. Small settlements are generally numerous, while large ones are fewer. Compared with small towns, larger urban centres usually offer more specialised services and serve a wider surrounding area.

Size and function are related, but they aren't identical. A relatively small administrative capital may be more politically important than a larger industrial city.

An urban agglomeration with at least 10 million inhabitants is a megacity. This population is the continuous urban concentration, which does not necessarily fall within a single municipal boundary. Megacities sit at the upper end of the population hierarchy and contain extensive, varied land uses. Size alone doesn't tell us how wealthy or well planned they are, or how much global influence they have.

Planned and spontaneous growth

Urban growth is an increase in population, built-up area or both. With Planned growth, development follows an intentional framework. Spontaneous growth takes place incrementally, without an overall coordinated plan.

These describe processes, not fixed categories of city. Within one urban area, a planned centre can sit alongside formally developed suburbs and spontaneously built neighbourhoods. Spontaneous growth isn't automatically informal or poor. Nor does planned growth guarantee adequate housing or services.

Activities and the central business district

Retail activity sells goods to consumers. Commercial activity covers offices and business services, while industrial activity produces or processes goods. Retail is commercial in the broad sense, but treating shops separately from offices helps explain why their location needs differ.

The central business district (CBD) is a city's main concentration of shops, offices and business services. Accessibility is commonly high here. Land is expensive and development intensive, though the CBD need not sit at the geometric centre of the present-day urban area.

Land values and proximity to the CBD

Land value is the price land can command; rent is what users pay to use it. Users compete for accessible locations, pushing land values up. Those activities that benefit most from central access can often afford the more expensive sites.

Busy streets can justify high rents for retailers: pedestrian flows increase potential sales. Offices benefit from access to clients and other firms, as well as transport. With land so costly, these activities tend to use relatively small plots or occupy multi-storey buildings.

Large factories and warehouses usually need more space than central shops or offices, so many favour cheaper peripheral sites with good road or rail access. Yet some older industrial areas remain near the centre. They developed when railways, docks or inner-city labour supplies were particularly important.

Physical factors

On flat land, large industrial buildings, storage yards and vehicle access are easier to construct. Ports attract activities that need access to shipping. Suitable water supplies may also favour particular industries. Steep slopes, unstable ground and flood risk can make development more costly or prevent construction.

Physical advantages alone aren't enough. Without transport access, a flat peripheral site may remain unattractive. An expensive central site, by contrast, may still suit a business that depends on face-to-face contact.

Planning and changing patterns

Planning authorities shape economic land use through zoning, which allocates areas to particular uses. Their decisions about infrastructure and development permission also influence land use. Industrial estates can concentrate manufacturing away from housing; restrictions on large peripheral shops can help keep retail activity in established centres.

New roads and serviced land can draw warehouses, business parks and shopping centres towards the urban edge. The CBD may still retain specialised offices and high-value retail. Urban economic patterns reflect how physical conditions and competing land bids interact with accessibility and planning—not just distance from the centre.

Physical factors and residential desirability

Residential areas are parts of an urban settlement used mainly for housing. Where they develop reflects household preferences, but also what households can afford or access.

Well-drained ground can increase demand and housing prices, as can attractive views and proximity to open space. Flood-prone land may be less desirable. The same applies to steep unstable slopes or locations exposed to industrial pollution. Elevation has no single effect: a stable hillside with views can attract expensive housing, while an unstable slope with poor access may accommodate households excluded from safer land.

Land values and ability to pay

Households compete for both housing and location. When land values are high, they encourage smaller plots and apartments, with greater building density, although planning restrictions may prevent this. Where land is cheaper, larger homes and gardens are often easier to provide.

Higher-income households have more freedom to choose accessible or attractive locations. For lower-income households, unaffordable alternatives may mean accepting overcrowding or smaller dwellings. They may also face environmental risk or longer journeys.

Wealthy residents don't always live in the suburbs, nor do poorer residents always live near the centre. Some cities have prestigious central apartments; others have affluent outer suburbs. Low-income housing may be found in older inner districts or peripheral estates, as well as in informal settlements.

Ethnicity and residential clustering

Ethnicity refers to a shared cultural identity associated with characteristics such as ancestry, language or traditions. Households may form ethnic residential clusters as they seek family networks and familiar shops. Places of worship, along with support in finding work or accommodation, can also draw households to these areas.

Clustering isn't always a free choice. Discrimination can limit where people live, as can unequal incomes and restricted access to housing. Residential segregation is the spatial separation of population groups into different neighbourhoods; it can reflect community preference as well as exclusion.

Planning and the combined pattern

Planning determines where housing can be built and the density permitted. It also determines the location of transport and public services. Public housing can concentrate lower-income households in particular districts, while mixed-income developments can bring different groups into the same area. Restrictions on plot size or building density may also put some neighbourhoods beyond poorer households' budgets.

Residential patterns shift as land values and population composition change, and as planning decisions change. Improved access or services can increase demand for a neighbourhood, making it less affordable to some existing residents.

Poverty and deprivation

Poverty is a lack of sufficient resources to meet basic needs or an accepted minimum living standard. Absolute poverty refers to a basic-needs threshold. Relative poverty refers to disadvantage compared with the living standards that prevail in a society.

Deprivation is disadvantage caused by inadequate access to resources, services and opportunities. It may take the form of poor housing or limited education or healthcare. Insecure employment and an unsafe environment can also be involved. Income poverty and deprivation often overlap, but they aren't interchangeable. Service provision and living costs also shape a household's circumstances.

The incidence of poverty or deprivation describes how widespread it is within a population. A city-wide average can hide sharp differences between neighbourhoods. Even a prosperous city may have districts where unemployment and overcrowding are concentrated, alongside poor access to services.

Informal housing

Informal housing is housing developed or occupied outside some or all formal systems of planning permission, building regulation and land tenure. The distinction rests on legal and administrative status, not simply on the materials used to build a dwelling.

When demand for affordable accommodation exceeds formal provision, informal settlements can expand. Low or insecure incomes make formal housing harder to access, as do expensive land and slow planning processes. Residents may occupy peripheral land or transport margins. Others may settle on floodplains or unstable slopes. These locations face less competition or are difficult to develop formally.

Services may be incomplete. Insecure tenure can discourage investment or leave residents exposed to eviction. Yet conditions vary: some settlements have durable buildings and established businesses, with services that are improving. Residents aren't all equally poor.

Informal industry and employment

Informal economic activity operates outside some or all formal registration, taxation and labour regulation. Small-scale production, such as furniture making, food processing or repair work in homes and workshops, forms part of informal industry.

Where formal jobs are insufficient or hard to access, these activities provide income. Low entry costs encourage clustering in residential neighbourhoods and busy urban locations, as does proximity to customers or labour. Workers may, however, face uncertain earnings and unsafe conditions, with limited employment protection. Informal production can also supply formal businesses. The two sectors are therefore connected, rather than separate economies.

Variation with urban development

Informal activity and poorly serviced settlements can be widespread where urban population growth outpaces the provision of formal employment, housing and infrastructure. Limited household incomes add to these pressures. Weak municipal resources reinforce them too.

In wealthier urban economies, formal housing and services usually reach a larger share of residents. Poverty and deprivation still persist. High housing costs and unemployment, along with discrimination and insecure work, can produce homelessness, overcrowding or disadvantaged neighbourhoods. Unregistered work and production can continue as well.

Development isn't a simple progression from an entirely informal city to an entirely formal one. Compare how prevalent poverty is and where it occurs. Examine access to services, housing security and opportunities for formal work. National development levels matter, but local inequality and the pace of urban growth help explain differences in conditions between cities and within them.