For Philadelphia to reach collections parity with other big U.S. cities and reduce its overwhelming delinquency inventory to more manageable levels is a job that will require not just new thinking, but persistence. A problem of this scale took decades to develop (there are nearly 9,500 properties in Philadelphia that are 20 or more years in arrears on their taxes), and it could well take multiple mayoral administrations to make right. The recent reforms and the legislative changes are intended to accomplish just that.