"There have been many more deaths due to ATVs than I ever imagined," Brown said. "It's a public-safety issue we could do something about."
After the mayor signs the bill, the law will go into effect March 1, 2013. Riding ATVs - intended as off-road vehicles - in the streets is already barred under state law.
Critics say that ATVs are dangerous and inflict costly damage on city parks.
"It endangers our users and scares people away from using our parks," said Parks and Recreation Commissioner Michael DiBerardinis. "And it costs hundreds of thousands of dollars of damage - which we don't have - to put into the repair and restoration of these areas."
At a public hearing on the legislation earlier this month, city public safety director Mike Resnick said that there were 16 ATV wrecks in Philly between 2010 and 2011. Three were fatal.
ATVs confiscated by police were typically sold back to riders at public auction. Under the new rules, the city could destroy seized vehicles.
Still, riders frequently complain that there is no city location to use their ATVs. Brown said she wants to continue working on the issue, hoping eventually to create a dedicated ATV park in Philadelphia.
DiBerardinis said that creating an ATV park would be "a bad use of scarce public dollars." But Brown said she was exploring getting money from local businesses. And she said that she plans to visit an ATV park in Egg Harbor, N.J., before the year is out.
"I'm going to get on the ATV to see what's the thrill," she said.
Riders said they hope that Brown will keep her word.
"I understand, she's a Councilwoman, somebody [citizens against ATVs] drops a problem in her lap, and she's gotta do something about it," said Dana Catlett, 37, a rider from West Philly. "But we're dropping a problem in her lap, too: We have nowhere to ride here. So if you don't stay to your word of building a park, then you're going to have a problem. Riders will say: 'Catch me if you can.' "
Contact Catherine Lucey at email@example.com or 215-854-4172. Follow her on Twitter @PhillyClout. Read her blog at phillyclout.com.