"There is no credible threat," he said. "That doesn't mean we don't stay vigilant."
"Obviously, our public safety team stays vigilant," Emanuel said, referring to the Police and Fire departments and the Office of Emergency Management and Communications. "But I also expect the public to stay vigilant.
"If you see something, say something," Emanuel added, repeating a familiar public safety mantra.
The mayor dismissed any concerns about the Chicago Marathon or public safety in general in the city, saying, "The Chicago Marathon will go on, as will all the big events."
Emanuel cheered the first responders in Boston, but also "what citizens did for other citizens," adding, "While it was a horrific event, it showed the best of this country."
Emanuel said he had called Boston Mayor Thomas Menino, as had the Police and Fire superintendents calling their Boston counterparts. Their message, he said, was that "if you need something from Chicago, we're ready to help in any way, shape or form."
Emanuel said he'd wait for findings on the bombing to be settled on and released, but that the city's public safety heads would study those findings "so Chicago can learn from this."
There was little evidence of any sort of heightened security at City Hall Tuesday, but for a few mounted police officers stationed outside at midday.
Emanuel made the comments at a news conference on expanding low-cost Internet access across the South and West sides held at the Avalon Library.