Ethnic succession theory is a theory in sociology stating that ethnic and racial groups entering a new area may settle in older neighborhoods or urban areas until achieving economic parity with certain economic classes. The concept of succession is well established in "both ecological and economic models of urban residential change." As the newer group becomes economically successful, it moves to a better residential area. With continued immigration, a new ethnic group will settle in the older neighborhood in a similar starting situation. This pattern will continue, creating a succession of groups moving through the neighborhood (and city) over time. Ethnic succession has taken place in most major United States cities, but is most well known in New York City, where this process has been observed since the 19th century. Explanations Immigration and environment Because of the United States' continued attraction for immigrants, its cities have been sources of study for scholars of urban development and ethnic succession. Ethnic groups often settle together in urban neighborhoods as part of a "chain of immigration" to a new country, or migration to a new region, to keep personal networks, languages, foods, religions and cultures alive. They may be viewed by the dominant racial or cultural group as undesirable neighbors because of prejudice against a new culture's dominating a neighborhood. People with entry-level skills and/or limited language skills often have settled in older areas, where they can afford the housing and entry-level jobs. Over time, the incoming group members find work, and members are able to establish themselves economically. The group rises in status with its economic achievements. The first, more established group tends to move out in the face of new arrivals, as it tends to have the economic resources to do so. The neighborhood takes on new demographics. Since the late twentieth century, more people in the United States live in suburbs than in center cities. Ethnic succession has also been observed taking place in suburbs, with newer groups settling in older suburbs, and more established groups' moving to newer developments. Many well-educated Indian and Nigerian immigrants, who could afford good housing, have settled immediately in better suburbs rather than in cities. Segregation Segregation has played a major part in the limitations on socioeconomic ascension of an ethnic group, whether by self-selection in settlement together or pressure to be confined by a majority group. In some cases, immigrants have been limited