The phenomenon of upper and middle class whites moving out of cities and into the suburbs is known as white flight. The opposite of white flight is gentrification, a process in which wealthy whites move back into an urban area, displacing the current residents and rapidly driving up the cost of living so that the previous residents are forced to move. Both practices have been extensively documented by students of demographics and urban development. White flight, in particular, has negative connotations, especially for those left behind in the suddenly impoverished neighborhood.

White flight began on a large scale after the Second World War, when African-Americans began to try to establish homes in America's cities. Many of these men and women were starting to enter the middle class themselves, with good jobs, education, and community values. However, racism led whites to attempt to force blacks out. When this proved unsuccessful, the white population moved to the suburbs, establishing new and primarily racially homogeneous communities. This practice was termed "white flight," and resulted in class and racial segregation in many American cities.

Several practices including redlining and restrictive covenants keep neighborhoods racially segregated. Redlining refers to the practice of denying goods and services to people in certain neighborhoods. It is a reference to the red line which used to be drawn on banking maps, indicating a neighborhood which would not be invested in. Mortgage discrimination is also an important part of redlining, essentially forcing minorities to buy property in certain regions only, assuming that they can buy property at all. This practice is illegal, and is prosecuted when proof that it is occurring can be supplied. Restrictive covenants are terms in a lease or bill of sale which dictate how the property is to be used, and although it is illegal to discriminate on the basis of race, many such covenants are on a thin line between discrimination and perfectly legal action.

A number of factors contribute to white flight. The first is racism, especially with growing numbers of immigrants from other countries, such as Latin American and Asian nations. Some whites may have a perception that crime rates are higher in neighborhoods with a high concentration of minorities, which may or may not be true. Some are simply racist. In both cases, they move.

Blockbusting, a real estate practice, also contributed to historical white flight, and may continue to to do today in some regions. Blockbusting refers to the sale of a property in a primarily white neighborhood to a black family, facilitated by a realtor. When neighboring white households learn of the sale, they fear their their property values will go down, and sell their properties, vanishing into the suburbs. Meanwhile, the realtor stands to make a significant profit.

A number of Americans and communities are harmed by white flight. White flight causes neighborhoods abandoned to decline, because wealthy families are no longer supporting their neighborhoods. As a result, the gap in access to education and services between rich and poor grows much wider. The racial segregation caused by white flight also leads to lack of cultural exchange and enrichment. Several institutions and organizations are working in the United States to decrease white flight, encouraging the establishment of rich multicultural neighborhoods.