Two-thirds of the world’s population will reside in cities by 2050. That’s why the mayors of the largest cities are taking the lead in global governance, picking up the baton dropped by central governments impeded by ideology or corruption. In fact, at a lunch in New York City, the Mayor of Chicago, Rahm Emanuel, speculated about the possibility of “city-states” moving ahead on environment, transport and education as authority is dispersed to those able to find solutions.

Emanuel was clear in his vision for a large city. It begins with education. The universities are the crown jewel, incubators of new companies. The community colleges have been aligned around industry specialties, and the curriculum is co-created with the large companies in the area (for example, the healthcare college has input from Abbott, Baxter and Blue Cross). The high school graduation rate has improved substantially, especially for young males, with more power given to school principals to adapt curriculum and a longer school day negotiated in the last labor contract.

The transport system is another key to the future. Emanuel has negotiated the third runway for O’Hare Airport, substantially increasing capacity, while pushing forward with a new international terminal. He is implementing a tax on ride-sharing, which will help to fund repairs to mass transit.

Chicago has also become a location of choice for corporate headquarters, attracting companies from smaller cities in the state or in the region. Con-Agra, ADM, Caterpillar, McDonalds, Motorola and Boeing are now all downtown. The mayor created a food incubator in a lower-middle-class area, Garfield Park, partly funded by large food companies in the city, such as Kraft, Kellogg and Con-Agra, with the aim of generating new products and entrepreneurial ventures.

The mayor was deeply passionate about finding a solution to inequality. He attracted Whole Foods to the Woodlawn area, providing jobs and fresh fruit and vegetables in the struggling neighborhood. While violence continues to challenge the city, he was confident that an increased police presence and better economic prospects were beginning to turn the tide. This optimism is echoed by Pastor Corey Brooks, director of Operation H.O.O.D, which plans to build a youth center in that same vicinity. Brooks has adopted 100 young people who have been placed on probation by the juvenile court. He puts them in construction or local retail jobs, which has yielded a significant decline in crime.

A more visionary effort at reimagining cities was evident at the Chicago Architecture Biennial. Architects from around the world were asked to reimagine Chicago’s landmark Tribune Tower, which has an imposing, Gothic look, designed by its then-owner Colonel McCormick. My favorite was an entry from Mexico City that envisaged a vertical city within a building, 192 plots of land that encompass every aspect of city life from shopping to soccer to housing.

I was reminded of the vitality of cities today as I walked to the 9/11 Memorial Museum in New York City, past the site of Tuesday’s brutal killing of eight innocent people by a crazed man intent on murder on Halloween. The stoic reaction of New Yorkers was to put up a remembrance at the Survivor Tree, the only bit of nature to come through the 9/11 terror attack, then to go about their business. Whether these tragedies occur in London, Manchester, Paris or New York City, we will not be intimidated.

Richard Edelman is president and CEO.

Pedro Lastra