A planet of smarter cities By 2050, city dwellers are expected to make up 70 percent of the Earth's total population, spiking from approximately 3.3 billion people today to a breathtaking 6.4 billion. That gives us only 40 years to prepare our cities and our planet for an inflow of new inhabitants comparable to more than 10 United States of Americas. How do we prepare our cities to absorb this many people? How must our cities transform to handle exponentially greater economic, societal and environmental complexity? Let's build a smarter planet, city by city.