In response to the acts of targeted violence occurring in the United States, the U.S. Secret Service National Threat Assessment Center (NTAC) has published this research report. The study was conducted for the specific purpose of identifying key information that will enhance efforts to prevent these types of attacks, building on the findings identified in its 2017 report.
https://www.secretservice.gov/data/press/reports/USSS_FY2019_MAPS.pdf