Summary
Highlights
Every day for the next 35 years, an average of 170,000 people will move to, or be born in cities in the developing world. Cities are popular because they are full of jobs, art, and community. Cities are good for the planet because their compact nature means that water, power, transportation, building materials, and land can be used with great efficiency.
Cities are not always the super-compact islands of utopic awesomeness we imagine. They are usually made up of urban cores surrounded by less dense residential, commercial, and industrial zones that sprawl on endlessly. People in suburbs use more energy, water, and other resources and emit more pollutants than those in taller, denser urban neighborhoods. They travel further to work and school, have more cars, and drive them further. They heat and cool bigger homes and tend bigger yards. These actions negate the compact efficiency of the dense urban cores they surround. Cities worldwide are expanding twice as fast in area as they are in population, which means they use more land and energy per person.
We could reverse this trend by getting rid of resource-hungry suburban sprawl. However, this is not how cities tend to develop organically. Policies allow us to influence the shape of our cities. Investing in mass transit and boosting gas prices encourages people to ditch their cars and live closer to each other. Mixed zoning laws allow people to work and play closer to home. When people live densely, they use resources less intensely. We have a choice: sprawl or grow tall.