Between traffic-light cameras, blue-light cameras that scan neighborhoods for violent crime, cameras on board city trains and buses —not to mention private security cameras— there are few places you can go in Chicago without being monitored. In the metropolis known as the City of Big Shoulders, it seems Big Brother really is watching.

At last count, there were an estimated 24,000 cameras in place. And the proliferation of cameras is raising new privacy concerns.

"It’s really a mission creep in terms of what those cameras were designed to do,” said Ed Yohnko, with the American Civil Liberties Union.

The basic rule with cameras is that people are free to record anything that happens in public because there is no expectation of privacy. But it gets more complicated, particularly with traffic cameras. Three-hundred-and-forty-eight cameras were at one point installed around the city, sold to the public on the claim that their purpose was to catch people speeding and running red lights.

Now, two-thirds of those cameras are being upgraded with 360-degree swivels so they can rotate and monitor everything within sight of the intersection.

That prompted the ACLU to raise the red flag. “They were implemented and sold to the public on the basis of the fact that they were going to be used for traffic safety,” Yohnko said. “But what this new [technology] permits is for these cameras to now be integrated into the massive surveillance system the city of Chicago already has.”