Kriston Capps reports on a surprising but valuable source of data on housing: the United States Postal Service (USPS). "The Address Management System is a dataset compiled by USPS mail carriers and updated on the go as they perform their duties. Rain or shine, more than 307,000 mail carriers deliver mail to U.S. addresses nearly every day of the week. Mail carriers also compile parcel-level vacancy data to increase postal efficiencies, specifically by noting vacancies. These data help USPS clean up address lists that the agency provides to bulk mailers, among other things."
Since 2004, the U.S. Department of Housing and Urban Development has received USPS's national address data (while preserving privacy of address-holders). Every quarter, however, "USPS hands [the data] over to HUD—in the form of ZIP+4 Code-level data aggregated to the 2010 U.S. Census Tract level."
"Once the data are geocoded to the Census Tract level (a proxy for neighborhoods), HUD shares the data with non-profit and research organizations who apply for access."
Capps cites the expertise of Sarah Duda, associate director Institute for Housing Studies at DePaul University, in explaining the value of the data. "There's no better dataset for tracking blight in Chicago, Duda says. Chicago's data for building violations, for example, are skewed by the fact that multifamily buildings require more permits and inspections than single-family units. And 40 percent of calls to 311 in Chicago are duplicate requests."