Mayor Michael R. Bloomberg is well known for tapping his own fortune to fill in gaps in the city's resources, whether spending millions of dollars to renovate Gracie Mansion or keeping the kitchen in the City Hall bullpen stocked with healthy snacks for his staff.
But it turns out Mr. Bloomberg has also been good at getting other philanthropists to fund social and educational programs, disaster relief efforts and other initiatives undertaken by the city with private help.
A report commissioned by Mr. Bloomberg's foundation, Bloomberg Philanthropies, has found that, over the last 12 years, the administration attracted $1.4 billion in noncity financing for programs that include planting trees and offering cognitive behavioral therapy to teenage inmates at Rikers Island. Some of that money was federal funds managed by nonprofit agencies, but a large majority was private.
A spokeswoman for Mr. Bloomberg said about 8 percent of the $1.4 billion came from the mayor himself. The other 92 percent, well over $1 billion, came from other donors.
Tom Freedman, who served in the Clinton administration as senior adviser to the president and is now a consultant, wrote the report, which Mr. Bloomberg will discuss on Thursday at an investors conference hosted by the Robin Hood Foundation.
He said that Mr. Bloomberg's experience in business and philanthropy gave him an unusual ability to understand how businesses, government and nonprofit groups could work together.
"He uniquely was able to understand all three sides of the potential partnerships," Mr. Freedman said. "That at least initially gave him an important advantage in using this tool."
Most of the funds have been raised through three nonprofit groups: the Mayor's Fund to Advance New York City, the Fund for Public Schools and the Fund for Public Health.
The public-private initiatives by the Bloomberg administration have included the High Line, a park on a former elevated railway, which has been financed in part by $110 million in donations from people such as Diane von Furstenberg and corporations such as Coach and AT&T; and NYC Green Carts, which has given permits and technical and marketing aid to mobile food carts to sell fruits and vegetables in neighborhoods where these are not readily available.
After Hurricane Sandy, the Mayor's Fund raised over $60 million from some 21,000 donors and over $7 million in goods and services to help storm victims. The money has paid for mold treatment for flooded homes, grants to small businesses, home repairs, and legal help for immigrants, among other things.
As a billionaire and a former chief executive, Mr. Bloomberg had privileged access to the corporations and philanthropists who could fund private initiatives, Darren Walker, the president of the Ford Foundation, said.
"Mayor Bloomberg has brought a unique set of qualities and capacities that most mayors don't have," he said.
But he and others interviewed were optimistic that Mayor-elect Bill de Blasio would be able to attract similar private support after he takes office in January.
"I think the private sector is eager to support Mayor-elect de Blasio," David Saltzman, the executive director of the Robin Hood Foundation, said. "The private sector loves New York City and cares about the future of this city."