How can we build the sort of cities we want to live in 20 years from now? How can we ensure that ordinary workers aren’t priced out of the communities they serve, and that cities are engines of opportunity for all? Later this year, there will be a rare opportunity to rethink our urban spaces as the UN hosts its Habitat III meeting in Ecuador.

The timing is crucial. Currently, 54% of the world’s 7.3 billion people live in urban areas; by 2045 the number of city dwellers is expected to grow by another 2 billion. We have reached a tipping point in terms of housing city-dwellers and meeting the needs for infrastructure.

At Habitat for Humanity, we continually see how families and communities build strength, stability and self-reliance through shelter. We know there are critical links between stable housing and better health, improved education outcomes and new livelihood opportunities. We see the ripple effects that occur when families—including low-income families— improve their living situations. One of the benefits we often observe through our housing finance work is the development of new markets for products and services.

Police officers, teachers and hospital workers are priced out”

Providing adequate and affordable housing is an issue that both the developing and the developed world must address. You needn’t look beyond cities like San Francisco, London or Mumbai to see how the challenges of accessing land and affordable housing impact millions of people.

Virtually nowhere in the U.S., for example, can a full-time minimum wage employee afford a one-bedroom apartment. Even when two people are pooling their full-time, minimum wage paychecks, they cannot pay the rent for a two-bedroom apartment in 29 states or the District of Columbia. Therefore, service workers—like police officers, teachers, hospital workers and firefighters—are being priced out of the very cities that depend on them.

Housing is finally on the agenda

Last September, representatives of 193 governments came together to develop specific plans for making the world a better place. They adopted 17 Global Goals designed to end poverty, combat climate change, and fight injustice and inequality. Imagine a strategic plan that will shape the way governments approach development for years to come. It is significant that these goals, unlike the Millennium Development Goals adopted in 2000, include a specific target concerning housing. For housing to make the list, world leaders had to view it as just as important as food, health, education, water and other priorities.

The next crucial milestone for the development of our cities is the Habitat III meeting, an event which only happens every 20 years and which will be crucial to developing a “New Urban Agenda” to guide the next wave of urbanization.

The meeting will attract important decision-makers from around the world, such as housing and finance ministers, ambassadors, heads of state and local government, members of the private sector and civil society organizations. They will decide what to do about cities, housing and land for the next two decades. With an emphasis on addressing poverty and how to end it, Habitat III will be the first chance for stakeholders from all three sectors to expand on the recently adopted cities and human settlements goal (Global Goal 11).

Staggering inequalities, invisible borders

An effective New Urban Agenda will be a measurable, forward-looking and action-oriented document providing guidance and specific steps that can help create thriving places to live and work. Those drafting the document cannot ignore the staggering inequalities that are present in urban spaces—the invisible borders that take the form of social, cultural and economic exclusion.

A New Urban Agenda should truly respond to priorities, needs and experiences of citizens, especially the poor in urban areas and other human settlements around the world. It must address issues like infrastructure, transportation, housing, health, jobs, access to food and education. It should not be limited to the problems and challenges of urban centers, however. It should also identify opportunities and advantages.

For example, cities can be powerful engines for economic growth. According to the World Bank, more than 80% of global gross domestic product is generated in cities. Urban residents, filled with new ideas, can contribute to sustainable growth.

Cities have always been built by families building incrementally, but with the exponential growth in urban areas in the last century, we have to think in new ways. Though progress will take time, we have seen some great examples of cooperation and collaboration to make positive changes.

Medellin’s story: from murder capital to tourist magnet

In the city of Medellin, Colombia, I have seen firsthand the transformation of informal settlements. Decades ago, rapid growth, political struggles and drug trafficking forced many people into informal settlements on the hillsides above the city.

A place known as the murder capital of the world in 1991 was named Innovative City of the Year by the Urban Land Institute in 2013, and The New York Times recently promoted it as a friendly tourist destination.

What happened? Medellin’s rebirth can be attributed, at least in part, to strong local leaders and a series of smart urban planning decisions that are continuing to pay dividends. In a reversal of the general flow of events, the government created essential infrastructure to support those informal settlements—decades after they were established. A cable car system now connects the hillside neighborhoods to the subway system and businesses in the valley. What was a three-hour walk is now 20 minutes by cable car and subway.

Like any city, Medellin still faces challenges, but violence has declined and amenities such as libraries and pocket parks established by the government give people attractive places to gather. Other businesses began to spring up throughout the area, and Habitat for Humanity Colombia is part of the effort to improve housing in the settlements as well.

When the public, private and social sectors invest in housing, transportation, access to healthy food, education, healthcare and the like, they help create and support a vibrant workforce and an enabling environment for individuals and businesses to succeed. Our hope is that the New Urban Agenda will outline a smart and successful plan for empowering those who will need proper housing and access to basic infrastructure and services in the world’s cities in the next 20 years.

To learn how Habitat for Humanity is advocating for smart housing and land policies leading up to Habitat III, please visit solidgroundcampaign.org.