Cities have a way to go before they can be considered geniuses. But they’re getting smart pretty fast.

In just the past few years, mayors and other officials in cities across the country have begun to draw on the reams of data at their disposal—about income, burglaries, traffic, fires, illnesses, parking citations and more—to tackle many of the problems of urban life. Whether it’s making it easier for residents to find parking places, or guiding health inspectors to high-risk restaurants or giving smoke alarms to the households that are most likely to suffer fatal fires, big-data technologies are beginning to transform the way cities work.

Cities have just scratched the surface in using data to improve operations, but big changes are already under way in leading smart cities, says Stephen Goldsmith, a professor of government and director of the Innovations in Government Program at the Harvard Kennedy School. “In terms of city governance, we are at one of the most consequential periods in the last century,” he says.

Although cities have been using data in various forms for decades, the modern practice of civic analytics has only begun to take off in the past few years, thanks to a host of technological changes. Among them: the growth of cloud computing, which dramatically lowers the costs of storing information; new developments in machine learning, which put advanced analytical tools in the hands of city officials; the Internet of Things and the rise of inexpensive sensors that can track a vast array of information such as gunshots, traffic or air pollution; and the widespread use of smartphone apps and mobile devices that enable citizens and city workers alike to monitor problems and feed information about them back to city hall.

All this data collection raises understandable privacy concerns. Most cities have policies designed to safeguard citizen privacy and prevent the release of information that might identify any one individual. In theory, anyway. In reality, even when publicly available data is stripped of personally identifiable information, tech-savvy users can combine it with other data sets to figure out an awful lot of information about any individual. Widespread use of sensors and video can also present privacy risks unless precautions are taken. The technology “is forcing cities to confront questions of privacy that they haven’t had to confront before,” says Ben Green, a fellow at Harvard’s Berkman Klein Center for Internet and Society and lead author of a recent report on open-data privacy.

Still, cities are moving ahead, finding more ways to use the considerable amounts of data at their disposal. Here’s a look at some of the ways the information revolution is changing the way cities are run—and the lives of its residents.

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