An urban area is the region surrounding a city. Most inhabitants of urban areas have nonagricultural jobs. Urban areas are very developed, meaning there is a density of human structures such as houses, commercial buildings, roads, bridges, and railways.
"Urban area" can refer to towns, cities, and suburbs. An urban area includes the city itself, as well as the surrounding areas. Many urban areas are called metropolitan areas, or "greater," as in Greater New York or Greater London.
When two or more metropolitan areas grow until they combine, the result may be known as a megalopolis. In the United States, the urban area of Boston, Massachusetts, eventually spread as far south as Washington, D.C., creating the megalopolis of BosWash, or the Northeast Corridor.
Rural areas are the opposite of urban areas. Rural areas, often called "the country," have low population density and large amounts of undeveloped land. Usually, the difference between a rural area and an urban area is clear. But in developed countries with large populations, such as Japan, the difference is becoming less clear. In the United States, settlements with 2,500 inhabitants or more are defined as urban. In Japan, which is far more densely populated than the U.S., only settlements with 30,000 people or more are considered urban.
Throughout the world, the dominant pattern of migration within countries has been from rural to urban areas. This is partly because improved technology has decreased the need for agricultural workers and partly because cities are seen as offering greater economic opportunities. Most of the worlds people, however, still live in rural areas.
The western part of the United States, for instance, is dotted with "ghost towns." Ghost towns no longer have any human population. They are full of abandoned buildings and roads that have been overtaken by shrubs and natural vegetation.
Many ghost towns in the western U.S. are the remains of "boom towns," which developed after gold and silver were discovered in the area in the 19th century. Economic activity boomed in these towns, most of it centered on mining. When all the gold and silver was mined, economic activity stopped and people moved away, leaving ghost towns of empty homes and businesses.
Growth of Suburbs
Suburbs are smaller urban areas that surround cities. Most suburbs are less densely populated than cities. They serve as the residential area for much of the citys work force. The suburbs are made up of mostly single-family homes, stores, and services.
Many city residents move to suburbs, a situation known as suburban migration. Homes in suburbs are usually larger than homes in cities, and suburbs usually have more parks and open spaces. Residents may move to escape the traffic, noise, or to enjoy a larger residence.
At the end of World War II, the U.S. government enacted a program that gave home loans to returning war veterans. This created an explosion of single-family homes and increased the growth of suburbs across America.
The establishment of the Federal-Aid Highway Act of 1956 also contributed to the growth of suburbs and urban areas. The Highway Act created 66,000 kilometers (41,000 miles) of interstate roadway systems. The original plan for the highway system was for the evacuation of large cities in case of a nuclear or military attack. What the Highway Act created instead was suburban sprawl.
Suburban sprawl continues to be a phenomenon in the U.S. First, outlying areas of a city widen. Slowly, these outlying areas become more crowded, pushing the suburbs farther into rural areas.
Housing and businesses that serve suburban communities eat up farmland and wilderness. More than 809,000 hectares (2 million acres) of farmland and wilderness are lost to development every year in the U.S.
Recently, experts have tried to curb the spread of suburban sprawl, or at least create urban areas that are developed more purposefully. This is known as "smart growth." City planners create communities that are designed for more walking and less dependency on cars. Some developers recover old communities in downtown urban areas, rather than develop the next piece of farmland or wilderness.
States such as Oregon are passing laws to prevent unplanned urban sprawl. They have created boundaries around cities that limit the growth of development. Officials have created laws stating that the minimum size of a plot of land is 32 hectares (80 acres). This is to prevent developers from creating suburban communities. An 80-acre plot of land is too costly for a single-family home!
Other smart-growth communities are creating new types of development. Some have large amounts of undeveloped "green space," organic farms, and lakes.
Urban areas typically drain the water from rain and snow, which cannot collect in the paved-over ground. Rather than use drainage pipes and ditches, smart-growth communities create wetlands designed to filter storm runoff.
More city planners are developing urban areas by considering their geography. Engineers build structures that blend with their natural surroundings and use natural resources. White roofs, for example, reflect the suns rays and lower the cost of air conditioning. Homebuilders in urban areas as diverse as Los Angeles, California, and the island communities of Greece create homes and businesses with white plaster or tile roofs for this reason.
There is also a move toward preserving and maintaining more green areas and planting more trees in urban areas. Landscape designers often consult with city planners to incorporate parks with development.
One type of suburban migration is connected to the history of racism in the United States. After World War II, many African Americans migrated to cities in the north of the country, such as Philadelphia, New York, and Chicago. Some white residents of these cities then moved to the urban areas surrounding the cities, a suburban migration known as "white flight."
Phoenix, Arizona, one of the fastest growing communities in the U.S., has been spreading outward at the rate of an acre an hour.
to desert or leave entirely.
the art and science of cultivating the land for growing crops (farming) or raising livestock (ranching).
urban area that grows very rapidly due to economic opportunity.
megalopolis between Boston, Massachusetts, and Washington, D.C.
large settlement with a high population density.
person who plans the physical design and zoning of an urban center.
trade, or the exchange of goods and services.
having to do with the buying and selling of goods and services.
to travel to and from specific places on a regular basis, usually for a specific purpose, such as employment.
number of things of one kind in a given area.
main or most important.
tube that carries wastewater or other material away from a home or business.
situation for a person or group of people to improve their standard of living.
person who plans the building of things, such as structures (construction engineer) or substances (chemical engineer).
to leave or remove from a dangerous place.
area used for agriculture.
law approving construction of 66,000 kilometers (41,000 miles) of interstate roadway systems in the United States.
person who studies places and the relationships between people and their environments.
urban area that has been abandoned by all residents.
valuable chemical element with the symbol Au.
area of undeveloped land usually used for recreation.
unit of measure equal to 2.47 acres, or 10,000 square meters.
to blend or bring together.
numbered road that stretches between at least two U.S. states. Also called "I" followed by the roadway's number.
body of water surrounded by land.
person who studies and plans gardens, parks, and other "green spaces."
the union of two or more urban areas into a continuous metropolitan area. Also called a conurbation.
region surrounding a central city and has at least 15 percent of its residents working in the central city.
movement of a group of people or animals from one place to another.
process of extracting ore from the Earth.
a material that humans take from the natural environment to survive, to satisfy their needs, or to trade with others.
military aggression with explosive devices fueled by the interaction of atomic nuclei.
land cultivated for crops, livestock, or both, according to guidelines using limited amounts of chemicals.
land surrounding a specific point.
an unusual act or occurrence.
road constructed with metal tracks on which trains travel.
any area on Earth with one or more common characteristics. Regions are the basic units of geography.
regions with low population density and large amounts of undeveloped land. Also called "the country."
system of control of an area according to that area's residents.
type of plant, smaller than a tree but having woody branches.
chemical element with the symbol Ag.
residential structure that is not attached to another structure. Also called a detached house.
method of development that serves the community and the environment.
precipitation made of ice crystals.
rainwater from storms.
public transportation, usually electric, that runs on rails. Also known as a trolley.
geographic area, mostly residential, just outside the borders of an urban area.
movement of people from a city to its suburbs.
unplanned low-density development surrounding an urban area that often starts as rural land. Also called urban sprawl.
the science of using tools and complex machines to make human life easier or more profitable.
human settlement larger than a village and smaller than a city.
developed, densely populated area where most inhabitants have nonagricultural jobs.
all the plant life of a specific place.
person who has served their country in a military capacity.
small human settlement usually found in a rural setting.
area of land covered by shallow water or saturated by water.
environment that has remained essentially undisturbed by human activity.
number of people who are employed or available for employment.
(1939-1945) armed conflict between the Allies (represented by the United States, the United Kingdom, and the Soviet Union) and the Axis (represented by Germany, Italy, and Japan.)