This is the final article in a five-part series examining key urban challenges in American cities: Suburban sprawl | Gentrification | Big Data | Climate change | Diversity

To return to the much-quoted doyenne of urbanism Jane Jacobs, "cities have the capability of providing something for everybody, only because, and only when, they are created by everybody."

Faced with unprecedented levels of globalization and integration, urban planners and city managers are now under pressure to take into account a much broader range of perspectives and priorities as they refashion our urban spaces. Thus, managing diversity is our fifth and final urban challenge.

Living among strangers

In an age when identity politics is on the rise, the principles of diversity are under attack. However, America's cities are notably not the locus of this phenomenon. If there is one thing that distinguishes the experience of a city-dweller, it is the need to learn to live with strangers as your neighbors.

Cities throughout history have been more diverse than the states in which they are embedded. Traditionally, this has been dealt with by deliberately segregating ethnic groups into their respective "quarters" — as will become clear to anyone wandering through the historic Armenian and Jewish quarters of ancient Constantinople. Or more recently, New York's "Little Italy" or San Francisco's "Chinatown."

But as countries have become more urbanized in recent years, their cities are also becoming more globalized than ever. Immigration is now one of the most powerful forces shaping today's cities. Immigrants now account for 40 percent of U.S. population growth and for 50-75 percent of the growth of its metropolitan areas.

Some cities are actively attracting immigrants, seeing in them an opportunity for growth and vibrancy, and studies have found that America's "sanctuary cities" like New York, Chicago and Washington, D.C. (which make policies that welcome refugees and asylum seekers) are in fact safer than other cities.

However, anti-immigrant riots in other global cities — like Rome and Pretoria — highlight the challenges of integrating the unprecedented waves of migrants in the short term. İn the longer term, the challenge of dealing with anger over gentrification illustrates how diversity can in fact exacerbate urban fragmentation and further entrench racial and ethnic inequalities, rather than bring different perspectives together.

Women and public spaces

Managing diversity does not mean only taking into account those born elsewhere, but asking how other social groups may experience the city in different ways.

Cities are still largely designed by men and for men. But it is now widely acknowledged that men and women experience the city in very different ways. In particular, women are frequently excluded from the social mixing potential of quality gathering spaces. The need to design public spaces where women feel safe is another challenge being taken up by planners.

The Austrian capital of Vienna has become a pioneer in designing a city for women, since new data uncovered the vast difference between the way women move around the city compared to men. One housing project, called "Women-Work-City," is designed by women architects and planners to take full note of the distinct needs of women's everyday life.

Further research has been done on the experience Muslim women have of the built environment — leading us to explore how planners, architects and urban designers can meet the needs of this group. Participative urban planning has been suggested as one promising tool.

Whose problem?

Managing diversity is frequently seen as the domain of federal or regional governments, leaving the city with little role to play. However, while education, health and welfare policy-making is vital, migration policy experts point out that successfully diverse cities have a much finer grain — this is because social inclusion depends not only on basic services but also "on the quality of the countless interactions that occur among the kaleidoscope of individuals, social groups and institutions that exist in a city."

Essentially, while national governments can set out the broader framework within which social inclusion takes place, it is at the city level where social inclusion is lived and negotiated. This makes city-level governance increasingly influential.

Action at the city level can include intensified networking with nongovernmental bodies and community groups, and then designing policies and spaces that reach out to minority communities. It means taking the experience of immigrant communities into account in land use, in order to encourage "thick" and "thin" community links.

It also means taking a look at transportation planning in order to integrate immigrant workers into the life of the city. Multiple policy "solutions" are required for cities to take the lead on creating successful communities.

Thoughtful urban designers also becomes an important integrative asset, once we acknowledge public spaces as vital for community cohesion and as a platform for inclusion.

Diversity and segregation

Diversity, and encounters with the unfamiliar, is what makes city life so attractive to so many. But color-coded maps of "diverse" cities like Chicago show the realities of the mutual isolation of different ethnic groups in American cities.

Cities must be wary of mistaking diversity for segregation and must listen to communities and make the most of new tools like participative planning in order to meet the needs of all. Ensuring that the professional architecture and planning communities reflect the needs of the community they are serving also goes a long way to creating cities for and by everybody.