Washington police say cameras make the streets safer. Last year, three homicides and an assault on a police officer were captured on video, a police study found.
And in areas within 250 feet of a camera, violent crime declined 19% last year, the study said.
Critics say cameras simply move crime onto side streets, out of video range.
"When you measure the effectiveness of these cameras against the harm they do to civil liberties, there just doesn't seem to be a question for us," said Johnny Barnes, executive director of the National Capital Area chapter of the American Civil Liberties Union.
Among residents, cameras are popular, said Councilwoman Muriel Bowser, who represents a relatively affluent northern area of Washington.
"There's not a meeting or a community that I go into," she told her colleagues, "that doesn't tell us how cameras have positively impacted public safety in their neighborhoods."
Times staff writer Andrew Blankstein in Los Angeles contributed to this report.