Black families pay 13% more in property taxes each year than a white family would in the same situation, a massive new data analysis shows. Troup Howard and Carlos Avenancio-Leon, then working on doctorate degrees at the University of California, Berkeley, combined 118 million real estate transactions and assessments from 2005 to 2016 with maps of more than 75,000 local taxing entities - such as counties, school districts, airport authorities and utility districts. They used the maps to sort homes into areas that faced the same property tax burdens, identified the races of homeowners using federal mortgage data, and looked at every time a dwelling was assessed and then sold in the same year. That allowed them to compare a home's assessed value and its market value, alongside the homeowner's race and ethnicity.