Overall crime from Jan. 1-June 30 also decreased for the third straight year, down 15 percent from 2013.
U.S. Rep. Robin Kelly prepared what she called the "blueprint for ending the crisis" of gun violence.
The City Council passed a court-ordered ordinance for licensing gun shops.
But the mayor's ordinance would set strict rules for sales and for the location of gun shops.
"We're just hanging in there," said Nathaniel Pendleton on what would have been Hadiya's 17th birthday.
Mayor Rahm Emanuel planned to submit the ordinance at Wednesday's City Council meeting.
Mayor Rahm Emanuel called on all media, artists, entertainers and athletes to join the effort.
Mayor Rahm Emanuel erupted in anger over the Easter weekend's "senseless, meaningless violence."
Mayor Rahm Emanuel admitted that, at first, "we didn't really have a comprehensive anti-gang strategy."
The mayor will seek a six-month delay in a court order allowing gun shops in the city.
Rahm and McCarthy touted the study's findings to renew calls for after-school programs and gun control.
Aldermen Edward Burke and James Balcer proposed a ban on guns made with a 3-D printer.
Budget Director Alexandra Holt said overtime adds flexibility and puts more police on the street.
The Budget Committee tabled a measure to spend $25 million on more police officers.
"These officers are right here, right now," said police Supt. Garry McCarthy to justify overtime.
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