"Today, cities are back. The policing revolution—helped by the waning of the crack epidemic—made cities safe again. Core public services were slowly restored, parks were rebuilt, and transit systems were cleaned up and refurbished. Investment started returning. The structure of the economy changed, too. Starting in the 1990s, technology radically transformed the business world and is now a major industry in its own right. The financial industry was deregulated. Globalization drove demand for new types of business services, reinforcing the need to stay on top of a constantly shifting landscape. People with advanced, specialized knowledge are the ones who help companies innovate now. These employees work in highly interactive ways that benefit from clustering together—disproportionately in urban areas like New York, Chicago, and Boston."