ABSTRACTObjective:In January 2017, Washington, DC, hosted the 58th United States presidential inauguration. The DC Department of Health leveraged multiple health surveillance approaches, including syndromic surveillance (human and animal) and medical aid station-based patient tracking, to detect disease and injury associated with this mass gathering. METHODS: Patient data were collected from a regional syndromic surveillance system, medical aid stations, and an internet-based emergency department reporting system. Animal health data were collected from DC veterinary facilities. RESULTS: Of 174 703 chief complaints from human syndromic data, there were 6 inauguration-related alerts. Inauguration attendees who visited aid stations (n = 162) and emergency departments (n = 180) most commonly reported feeling faint/dizzy (n = 29; 17.9%) and pain/cramps (n = 34;18.9%). In animals, of 533 clinical signs reported, most were gastrointestinal (n = 237; 44.5%) and occurred in canines (n = 374; 70.2%). Ten animals that presented dead on arrival were investigated; no significant threats were identified. CONCLUSION: Use of multiple surveillance systems allowed for near-real-time detection and monitoring of disease and injury syndromes in humans and domestic animals potentially associated with inaugural events and in local health care systems.