In the United States, a metropolitan area is officially called a Metropolitan Statistical Area. Two or more adjacent metropolitan statistical areas form a Consolidated Metropolitan Statistical Area. U.S. metropolitan areas have at least one city or urban area with a population of 50,000 or more, and include the entire county in which the city is located. Adjacent counties may be considered part of the area, depending on their population density and the number of workers who commute to jobs in the central county. The term greater applied to a city refers to a metropolitan area, such as Greater Paris. In England, clusters of small cities around a large city are called metropolitan counties.

In developed countries, most people live in metropolitan areas. In the United States, about 80 percent of the people live in the nation's 268 metropolitan statistical areas. In Canada, about 60 percent of the people reside in 25 metropolitan areas.

As cities grow, people move beyond official city boundaries, creating suburbs. This process of sub urbanization has been going on since the late 1800's. Several factors contributed to the development of metropolitan areas. Originally, large numbers of people came from rural areas to central cities in search of employment. This population shift produced overcrowded cities, causing other people to move to outlying areas. The use of automobiles, together with the improvement of roads and highways, increased tremendously following the end of World War II in 1945. As a result, more and more people have settled in communities outside of central cities since the late 1940's.

By 1970, more people in U.S. metropolitan areas lived in suburbs than in central cities. But by the early 1980's, the rate of suburban growth had decreased for a number of reasons. For example, many people moved to the suburbs to avoid such problems of big cities as crime, housing shortages, and racial conflicts. However, as the suburbs grew larger, they developed the same problems. Urban revitalization programs drew some people back to central cities.

People who live in the suburbs of a central city have traditionally considered the city as their workplace because of its commercial and industrial activities. Suburbanites also use the city's cultural, professional, and recreational facilities and services. Since the 1950's, however, many businesses and industries have moved to the suburbs. Today, many suburbanites who once commuted to and from work in the city work, shop, and enjoy various recreational activities in the suburbs.

Government. Most metropolitan areas have no central government to handle problems that affect the entire area. In most cases, government is almost completely decentralized--that is, each city, town, village, or other community in the metropolitan area has its own government. Little or no relationship exists between these governments and that of the central city.

The metropolitan statistical areas in the United States contain such local governmental units as counties, townships, municipalities, school districts, and special districts. Each unit has considerable political independence and establishes its own policies. As a result, government in most metropolitan areas is characterized by overlapping authority, policy conflicts, and lack of cooperation in solving mutual problems.

Many people who live in a metropolitan area may be affected by government policies over which they have little or no control. For example, people who live in suburbs may vote in their suburb and, at the same time, own a business in the central city. Government policy decisions made in the city may affect the business, even though the suburbanite cannot vote on them.

Finances and taxation. The widespread movement from central cities to suburbs affects the financial position of all the communities involved. The central city experiences declining land values and the loss of tax revenues. Also, many people who move into the city are poor, and many who move out are wealthy. As a result, the city provides medical care and other services for large numbers of residents who cannot afford them. The relocation of industries and commercial activities to the suburbs deprives city residents of job opportunities and reduces the city's tax base. However, many suburban communities are almost completely residential. Such suburbs have few taxable businesses, and they therefore often have difficulty raising enough money to provide adequate levels of such essential services as police and fire protection and public education.

Many suburban residents use public facilities in the central city, including museums, parks, and sports arenas, all of which require expensive maintenance. Some cities have tried to tax suburban residents who work in the city or to charge nonresident fees for the use of city facilities. In most cases, suburbanites have successfully resisted such taxes. Some suburbs have attempted to impose a similar tax on city dwellers who work in the suburbs or use suburban facilities. Most of these attempts also have failed.

Property taxes are the major source of revenue for governmental units within a metropolitan area. As a result, the central city and its suburbs compete for such tax-paying developments as manufacturing plants, office buildings, and shopping centers. These types of developments pay high property taxes and use few expensive public services. But in recent years, many metropolitan areas have worked to slow or stop suburban growth in order to reduce the cost of maintaining roads, sewage systems, and other public utilities and to protect the suburban way of life.

Various types of plans have been devised in attempts to solve the governmental and financial problems of metropolitan areas. These plans try to provide efficient government and a well-balanced economic policy for an entire metropolitan area. In most cases, however, local governments want to retain control over such important activities as education, police and fire protection, and zoning. This desire for local political independence has hampered efforts to develop effective plans. In many countries, the national government and the state or provincial governments handle most issues concerning growth and development of metropolitan areas.

The chief programs used in providing more efficient government and public financing for metropolitan areas include
(1) annexation, (2) extramural jurisdiction, (3) county government, (4) special districts,
(5) metropolitan federation, and (6) tax sharing.

Annexation. Most cities grew to their present size through annexation, which involves absorbing the outlying areas. Today, however, suburban residents generally oppose this method because they do not want to lose governmental independence.

Extramural jurisdiction. Some states and provinces give central cities governmental control of areas outside their boundaries. For example, Alabama cities have powers for 11/2 or 3 miles (2.4 or 4.8 kilometers) outside their city limits, depending on their population. Powers of extramural jurisdiction, also called extraterritorial powers, include police protection and sanitary regulation. They also may cover taxation of businesses and the control of subdivisions beyond city lines.

County government in some states and provinces provides urban services for areas outside city limits. For example, California has county governments that supply health and welfare assistance, police and fire protection, and other services to such areas.

A metropolitan county government provides urban services for an entire county, including central cities. Dade County, Florida, which includes Greater Miami, operates under a metropolitan county government plan. Voters from Miami and from other cities and districts in the metropolitan area elect members of a governing commission. The commission carries out plans for serving and developing the entire county. Municipalities handle only local affairs.

City-county government operates in a number of cities, including New York City, St. Louis, and San Francisco. It combines city and county functions but does not include suburban development.

Special districts, also called municipal authorities, consist of two or more local units in a metropolitan area. They provide one or more specific government services, such as sewage disposal and water distribution. The governing boards of special districts have the power to levy taxes and to spend public money. Many districts also use the revenue from services to pay for construction, maintenance, and operation of facilities.

Districts and authorities have led to increased governmental unity. But they have added to, rather than reduced, the number of governmental units in metropolitan areas. One of the largest and most successful municipal authorities is the Port Authority of New York and New Jersey. It handles port development and transportation within about 25 miles (40 kilometers) of New York City, in New York and New Jersey. The Metropolitan Water District of Southern California serves about 15 million people in 300 communities, including Los Angeles.

Metropolitan federation combines all the local governments of a metropolitan area into a unit called a federated city. The local units retain their own identities and carry on certain functions that they are best suited to handle, such as education, zoning, and police protection. The federated city administers the remaining functions for the entire metropolitan area. It has the taxing power to finance such functions, plus the authority to establish and carry out policies.

Tax sharing allows communities in a metropolitan area to share the costs and benefits of development. In a tax-sharing plan, part of the revenue a community gains from a new tax-producing development is distributed among other communities that are affected by the development. For example, the construction of a shopping center in one community may cause heavier traffic in neighboring communities. Tax sharing would help the neighboring communities pay for the increased costs of maintaining their roads.

Since the late 1970's, many metropolitan areas have considered adopting tax-sharing plans. In the United States, such a plan operates in the Minneapolis-St. Paul metropolitan area. Under this plan, the communities contribute tax revenues to the plan according to the amount of increase in the assessed (estimated) value of business properties.