The "broken windows theory" says there's a link between the number of broken windows in a neighborhood and crime. Social scientists published their findings in 1982.
In Columbus, some folks are cleaning up their neighborhoods to make them safer, and they say it is working.
Ken Williams leaned over and grabbed a squashed paper cup and tossed it in a large trash can.
"We try to have a litter-free alley. As litter-free as possible," he said.
Since they moved into their Reinhard Avenue home on the south side of Columbus, Ken Williams and Allen Carrel have picked up trash in the alleys, and kept an eye on vacant properties.
Williams led a group of neighbors on a litter hunt. He pointed to a house with peeling paint, and overgrown shrubbery. One cat peered out of a broken, second-floor window. Another leaped across a yard with knee-high grass.
"Allen, we have to turn this in again," Williams called.
"High grass?" Carrel asked.
"High grass," Williams confirmed.
Neighbors often join the two men on their twice weekly efforts to clear the neighborhood of litter.
"That's one thing when you pick up trash in the neighborhood, you hear issues where people have concerns," Carrel said.
The work has paid off. Nine years ago, the vacant lot next door overflowed with trash. They cleared away the debris and started to mow it. With grant money, they bought the property and turned it into Ganther's Place, a garden and pocket park for everyone to enjoy. Now, neighbors meet monthly to discuss concerns, and gather here for holiday celebrations.
Williams and Carrel bought a lawn mower and keep it filled with gas, to encourage residents to mow their lawns. Most do, and have planted trees and flowers, and painted their homes as well. This once decaying neighborhood is coming back.
But blocks away, it's a different story. There are rotting apartments, vacant homes, broken windows, overgrown land, and litter.
"When you see litter on the ground, it is an immediate signal that no one cares. And when no one cares, that sends a message to our criminal element," said Sherri Palmer of Keep Columbus Beautiful.
She believes there's a link shown by researchers, between litter, decay, and crime. But when people clean up, she says there's a subtle message to criminals - we're watching, so go away.
"You want to pick up litter? We make it easy," she said.
This city division loans out tools, gloves, and vests for litter patrols, to help people Williams and Carrel reclaim their neighborhoods. Carrel said that new families have begun to move in.
He spotted a new neighbor who has begun to renovate an old house.
"Buy a lot more houses," Carrel urged him. "There's a lot more houses in the neighborhood."
The driver smiled and waved.
"I wish we could, man," he said.
Palmer said that people who wish to organize a litter clean-up campaign can click on the Keep Columbus Beautiful website and be loaned the tools for free.