(NYTIMES) — OAKLAND, Calif. — Federal grants of $7 million awarded to this city were meant largely to help thwart terror attacks at its bustling port. But instead, the money is going to a police initiative that will collect and analyze reams of surveillance data from around town — from gunshot-detection sensors in the barrios of East Oakland to license plate readers mounted on police cars patrolling the city’s upscale hills.

The new system, scheduled to begin next summer, is the latest example of how cities are compiling and processing large amounts of information, known as big data, for routine law enforcement. And the system underscores how technology has enabled the tracking of people in many aspects of life.

The police can monitor a fire hose of social media posts to look for evidence of criminal activities; transportation agencies can track commuters’ toll payments when drivers use an electronic pass; and the National Security Agency, as news reports this summer revealed, scooped up telephone records of millions of cellphone customers in the United States.

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