Saturday's citywide cleanup was the largest of its kind in U.S. history, Mayor Nutter announced this morning.

No other one-day city cleanup brought out so many volunteers or picked up so much trash, he said.

"Pretty much by any measurement, we knocked this one out of the park," he declared, citing confirmation from Keep America Beautiful officials.

Organizers had hoped to register 10,000 volunteers and collect 1 million pounds of trash.

Instead, an estimated 15,000 people participated and removed 2.56 million pounds of trash.

The city hoped to clean 10 recreation centers and 10 sites in Fairmount Park.

More than two dozen of each were actually cleaned.

"It far exceeded anything we thought about in the planning," Nutter said.

To keep the effort going, the city plans to step up measures against illegal dumpers and deploy more trash cans.

The city will announce if a date is set for a future cleanup.