Jennifer Martinez, a spokeswoman for the city of Chicago, said there are roughly 2,000 cameras in Chicago's network, which covers housing developments and transportation centers, but not private businesses.
Andrew Velasquez, director of the Office of Emergency Management and Communications in Chicago, said city officials believe the cameras, which were installed starting in 2001, are partly responsible for a decline in crime. Chicago reduced its homicide rate by 25 percent last year, resulting in a 38-year low.
"Having that extra set of eyes and ears out there has contributed to the Chicago Police Department's crime-fighting strategy," Velasquez said.
Two dozen cameras are outfitted with gunshot detection software. "There are acoustic sensors built into the cameras, so if there's a gunshot detected within the vicinity of the camera, that camera will focus on the area where there has been a shooting," Velasquez said. "There will be an alarm or an alert to tell the person watching."
O'Toole said she hopes to buy more cameras for Boston soon and is looking for ways, including donations from businesses, to pay for them, since federal homeland security money only covers the cost of the 19 cameras to be placed along the harbor to help guard tankers carrying liquefied natural gas against terrorist threat.
She said she only wants to put cameras in areas where there is strong community support for them.
However, she said the issue is raised at most crime watch meetings, suggesting widespread interest.