Patrick Kerkstra has spent years exploring Philadelphia's property-tax crisis. For this collaborative effort by The Inquirer, PlanPhilly, and AxisPhilly, he interviewed property owners, city officials, and redevelopment experts and analyzed millions of records in the city's property, delinquency, billing, and code-violation databases.

That reporting was complemented by a professional economic analysis of delinquency's impact on property values by Kevin Gillen, an economist at the University of Pennsylvania's Fels Institute of Government and one of the region's leading property-values experts (read his study at

To measure if and how home values are affected by nearby delinquent properties, the project examined changes in home prices before and after neighborhood properties became delinquent. The analysis also took into account the preexisting condition of housing in each neighborhood, along with other factors typically associated with delinquency., an alternative news website that covers city design, planning, and development issues, is a project of PennPraxis of the University of Pennsylvania. For additional coverage, go to is a nonprofit news organization on topics of public interest.

Contributors include PlanPhilly reporters Jared Brey and Ashley Hahn; researchers Evan Croen, James Robertson, and John Dailey; designer John Suvannavejh; and AxisPhilly news application editor Casey Thomas. Inquirer editors, photographers, and designers produced the package.

The project was made possible through funding to PlanPhilly by the William Penn Foundation.