2 Urbanization and the Growth of Cities
Learn how urbanization differs from city growth, what drives changes in urban populations, and how suburbs and connected communities reshape urban regions.
and city growth
describes a change in the share of a population living in urban settlements. , by contrast, means that the population of a particular city or urban region increases. The two processes are related but not identical: a city can grow without a country becoming more urban if its population rises at the same rate as the national population.
A country can also become more urban when rural communities are reclassified or incorporated into expanding urban areas. As a result, changes in urban population figures may reflect both population change and changes in how places are defined or counted.
How urban places are defined
Definitions of urban places vary among countries and organizations. Some classifications focus on population density and settlement size; others also consider administrative boundaries or connections such as commuting. Comparisons between cities therefore require consistent definitions.
In the United States, the Census Bureau defines urban areas based on densely developed territory; “rural” describes territory outside those areas.
Processes that change city populations
Three processes can change a city’s population:
: births exceed deaths among city residents.
: people move into or out of a city, either within a country or across national borders.
Boundary change and reclassification: growing settlements may be absorbed into a city or counted as urban under a revised statistical definition.
These processes can reinforce one another. For example, may expand a city’s workforce, while adds to its population over time. is important, but its contribution varies by place and period; it is not the only source of .
Why people move
Cities concentrate jobs, education, health care, services, markets, and social networks. These opportunities can attract people from rural areas and smaller towns, as well as from other countries. Conflict, environmental change, family ties, or limited livelihoods in a place of origin can also influence decisions to move.
are reasons a destination attracts people, while are pressures that encourage people to leave a place. does not happen in only one direction: people may move from cities to smaller communities, between cities, or from a central city to nearby suburbs. Decisions depend on circumstances such as available work, housing costs, transportation, safety, and family connections.
and outward growth
is the growth of population and development in areas around a central city. Suburbs may include homes, workplaces, shopping areas, schools, and industry, so they are not necessarily only residential. Growth can result from population increase, from central neighborhoods, new housing construction, or businesses relocating outward.
A family might move from a central city to a nearby suburb for a larger home while adults in the household continue to work in the city. In such a case, the central city’s population might grow slowly or even decline while the larger urban region continues to expand. Looking only at city-proper population can therefore give an incomplete picture of urban change.
The growth of densely settled suburbs beyond incorporated city boundaries prompted the adoption of an urbanized-area concept in the United States in 1950.
Understanding
may produce : development that is relatively low-density, dispersed, fragmented, or distant from existing built-up areas. Sprawl is not measured by one feature alone. Density, land-use pattern, and how continuous development is all matter.
Metropolitan regions and multiple centers
As cities and suburbs grow, they can form metropolitan regions: a city and surrounding communities connected by daily activities such as commuting, shopping, and access to services. These functional boundaries may cross municipal or county lines and may not match a city’s legal boundaries. One approach to defining functional urban areas includes an urban core and economically connected surrounding areas.
Urban regions can also become , with multiple centers of employment and activity rather than one dominant downtown. Suburban business districts, transportation hubs, and nearby towns may develop their own centers. Beyond suburbs, lie farther from the urban core and often combine low-density development with more open or rural land.
Urban and rural as a changing transition
The boundary between urban and rural can become a transition rather than a sharp line. A rural community near a growing city may become increasingly connected to it through commuting, new roads, housing, and services. At the same time, a region’s population may spread across several linked centers instead of concentrating in a single city.
Understanding urban change therefore requires looking beyond city limits to the wider region and considering population change, , reclassification, suburban development, and connections among communities.