Our urban school systems struggle because so many of their students live in poverty, but they also struggle because they were designed a hundred years ago, for an industrial society. In an increasing number of cities, they are being replaced by 21st century systems, in which the central administration does not operate all schools and employ all teachers. Instead, it steers the system but contracts with others to row--to operate many of the schools. The steering body, usually an elected school board and appointed superintendent but sometimes a mayor or appointed board, uses charters and contracts to open schools that meet emerging student needs. If they work, it expands them and replicates them. If they don't work, it replaces them. Every year, it replaces the worst performers, replicates the best, and develops new models to meet new needs. The result is continuous improvement. This new formula--autonomy, accountability, diversity of school designs, and parental choice--is simply more effective than the centralized, bureaucratic approach we inherited from the 20th century. Cities that embrace it, by expanding charter schools but also by treating more district schools like charters, are transforming the lives of their students. New Orleans, which has 92 percent of its students in charter schools, is the fastest improving city in America. Washington, D.C., with 46 percent in charters, is close on its heels. Denver, Memphis, Cleveland, Newark, and Camden, New Jersey, are all moving in the same direction.