Ralph Gentles and five other people spent each summer creating a map of every crack, every depression, every protrusion, every pothole in the sidewalks of New York City. We hear why, and we hear all the things their map does not include.

Manny Howard talks with Paul Tough about why he loved fighting in bars and on the street, and about how hard it is to quit. Manny is the author of My Empire of Dirt: How One Man Turned His Big-City Backyard into a Farm.