Many contemporary cities have enacted measures to prevent the continuous urban sprawl that results from their ever-growing populations. They reserve a portion of land for farms, parks, forests, and other such things. This is called a “greenbelt.”

The “metropolitan area” of a city is defined as all the areas surrounding a city that can be said to have a high-level of economic or social integration with the city. So, if the majority of people who live in an area outside of a city’s political limits still commute to the city for work, school, or recreation than that area is said to be within the city’s “metropolitan area.” The definition is based on economic and social integration, NOT on physical proximity.

The term “ghettoization” is used to refer to the degradation of inner cities in America. It occurs when affluent white Americans move out of inner cities to the suburbs and this population is replaced with much poorer populations. It occurred throughout the United States in the twentieth century and is one of the more significant problems facing American cities in the twenty-first century.

The term “megalopolis” is used to describe a stretch of land that contains multiple cities and connecting suburban regions. The stretch of land from Boston to Washington D.C. also includes New York City, Philadelphia, Baltimore, and all the attending suburban areas. It is a highly urbanized stretch of land and therefore it is called a “megalopolis.”

In major American cities, poor urban areas suffer from a variety of problems due to a few specific realities of their geographic locations. Poor inner-city neighborhoods are usually much more densely populated than their wealthier counterparts, but with fewer amenities due to their worse infrastructure. One of the best examples of the problems produced by these issues is the lack of quality food options from high-end grocers, farmers' markets, or specialty stores.

Agglomeration is a real-world marketing ploy in which establishments are located close to one another to help convince like-minded consumers who may walk out of one establishment and want to go to another. For example, coffee shops and sandwich shops tend to be located close to one another with the idea that customers may leave the coffee shop and want a sandwich, or vice versa. 

The Federal Government defines environmental justice as the official government policy that all American citizens deserve to be treated equally with regard to the passage and application of environmental laws— regardless of where they live. This policy emerged out of fear that environmental issues like pollution were disproportionately affecting lower-income communities.

The term “blockbusting” is used to refer to a common practice in the real estate business in the twentieth century (in some places it persists to this day). It involves a realtor trying to intimidate a white property owner into selling inner city property and moving to the suburbs. The realtor convinces the white property owner that the neighborhood is “in decline” due to the large numbers of minorities moving into the area. This process accelerated the rate of suburbanization in the twentieth century. Due to its obviously racist implications and manipulative nature “blockbusting” has long been controversial.

By definition, a squatter settlement is a collection of buildings aimed to provide housing and shelter for poor people in a city. The people who live in squatter settlements do not have legal rights to the land upon which they are built; therefore, they are living there illegally. Squatter settlements are a housing alternative when affordable housing is otherwise hard to come by in a city. 

“Counter urbanization” refers to the process by which a significant portion of the population of an urban center starts to migrate away from the city to live in suburbs or rural areas. This of course cannot happen without large-scale urbanization and the acquisition of wealth so it is most likely to occur in highly developed regions.