You’ve just heard that inequality and segregation are growing in most cities around the world, and this is a worrying trend. There is a lot of variation between countries regarding the level of inequality and segregation, but also regarding their drivers. It is generally acknowledged that very high levels of segregation can harm the social sustainability of cities, and have a negative impact on social mobility of people.

For example, the negative effects of high levels of inequality could be seen in South Africa under apartheid, or in many countries in South America, and include political instability, high rates of poverty and crime, and residential segregation with gated communities for the rich. Extremely high levels of inequality are thought to be harmful as they reduce intergenerational social mobility, partly through the operation of the vicious circle of inequality and segregation. Another extreme could be found in the formerly centrally planned countries in Eastern Europe – these had very low levels of inequality, and private housing property did not exist. In such a socio-political context, the individual motivation to be creative and to aspire to be economically productive are low, thus restricting economic growth.

Segregation is not necessarily problematic. In contemporary cities, most people live in neighbourhoods with others who are similar to themselves. However, extreme levels of socio-economic and ethnic segregation can harm the social sustainability of cities. Especially when these forms of segregation overlap, they are a concern for local and even national governments. High levels of segregation increase the risk that the rich and the poor live more and more separate lives. This might result in a drop of social cohesion, lead to estrangement and fear for others, and have a negative effect on social mobility. These risks increase when there are very clear spatial borders between distinct socio-economic areas within cities. For example, gated communities for the affluent who separate themselves from the rest of the population, and so-called no-go-areas with extreme concentrations of poverty and high levels of crime. Having said this, segregation can also be perceived as positive because many people prefer to live among similar others.