Cities are places of opportunity. In cities people can benefit from work and training opportunities, proximity to other people and physical access to many high-level services that are important for well-being. When cities are well-organised and inclusive, they allow people to access opportunities, regardless of their location within the city.

However, cities are often divided. In divided cities there are gaps and barriers that produce exclusive spaces and concentrations of disadvantage. Inequality in access to high-quality services and economic opportunities across social groups can exacerbate existing societal disparities. In this context, it becomes relevant to understand how social groups are organised within cities and how this relates to intra-urban inequalities.

International comparisons are helpful for putting measurements of such inequalities into perspective. Of particular relevance is the study of socio-economic spatial segregation, a situation where people of a similar background − in terms of income, culture, country of origin, etc.− live concentrated in certain parts of a city and clearly separated from other groups. Segregation can have both positive and negative sides, but it is deemed to be especially problematic when it is involuntary and when it leads to few interactions among the resident groups and less access to opportunities.

While segregation is a challenge in cities across the globe, international evidence and a systematic reflection on the different types of segregation and inequalities in access to opportunities is missing. As a response to the need for international comparable studies on intra-urban inequalities, the OECD, in partnership with the Gran Sasso Science Institute (GSSI), launched in 2016 a project to better understand the different dimensions of inequality within cities and metropolitan areas throughout OECD countries.

This report was realised as part of a larger effort of the Regional Development Policy Committee and its Working Party on Territorial Indicators and Working Party on Urban Policy to understand how to make cities more inclusive. Building on a previous report entitled Making Cities Work for All (2016), it provides an assessment of intra-urban inequalities in terms of income, migrant status and access to public transport in a subset of metropolitan areas in the OECD and beyond. Several indicators presented in this report at the scale of metropolitan areas will be included in the OECD Metropolitan Database and will contribute to making robust international comparisons of inequalities and segregation across cities in OECD countries.

The five authored chapters provide new insights on cross-cutting issues with respect to inequality and segregation from a multi-dimensional perspective. They examine, for example, the role of governance structures and housing types as determinants of segregation; the patterns of concentration of migrants across neighbourhoods; the role of public transport accessibility in widening intra-city inequalities; and expected path dependency on outcomes related to segregation. The report also discusses methodological alternatives for measuring different dimensions of inequality and segregation across cities and the limitations of these measurements.