From the Document: "It is difficult to measure the economic costs of gun violence because in the past Congress has blocked federal funding for research at the Centers for Disease Control. The more than 20-year ban has had a chilling effect on private and other research. More study is needed to better understand both the costs of gun violence and the actions that can be taken to reduce it. This report compiles estimates of the economic cost of gun violence in each state, based on data from the Giffords Law Center to Prevent Gun Violence and the Centers for Disease Control. It provides an estimate of the overall economic cost in each state and presents it as share of state gross domestic product. It also includes data on the annual number of homicides, suicides, non-fatal shootings and accidental shootings. It is likely that the numbers underestimate the total costs of gun violence."
U.S. Congress Joint Economic Committee: https://www.jec.senate.gov/public/