Over the next two weeks, Next City will unroll short profiles of 77 people, places and ideas that have changed cities this year. Together, they make up our 2012 Disruption Index. Forefront subscribers can download the Index in full as a PDF, complete with beautiful designs and graphics by Danni Sinisi. Readers who make a $75 donation to Next City will have a full-color printed copy of the Index mailed to them.

There are plenty of ways to compare neighborhoods, but one that’s becoming increasingly important is walkability. More and more Americans want to know how easy and safe it is to walk around a neighborhood and what sort of urban amenities they can access on foot. The best way to find out — aside from actually taking a walk — is Walk Score, the website that rates addresses by how easy it is to accomplish bipedal daily errands. Having become a crucial tool for pedestrian advocates, the site is also used by some of the biggest real estate services; the Walk Score of a neighborhood has become a new selling point for real estate agents and homebuyers.

Most recently, Walk Score has augmented its website and mobile app to allow people to add missing places to its map. Users can snap photos and upload descriptions of places in their neighborhoods, identifying areas where walkability could be improved. The thinking is that locals know what makes their neighborhood a good or bad place to walk. By tapping into this local crowd wisdom, Walk Score is aiming to become an even more trustworthy authority on navigating cities without a car.

Nate Berg is a writer and journalist covering cities, architecture and urban planning. Nate’s work has been published in a wide variety of publications, including the New York Times, NPR, Wired, Metropolis, Fast Company, Dwell, Architect, the Christian Science Monitor, LA Weekly and many others. He is a former staff writer at The Atlantic Cities and was previously an assistant editor at Planetizen.