Objective: The objective of this study is to determine the number of primary stroke centers (PSCs) that exist concurrently (synergic relationship) with designated higher level trauma centers (level I or level II trauma centers) and associated characteristics. Methods: We identified all PSCs certified by the Joint Commission or local state authorities in 2010. Concurrently, all the higher level trauma centers (designated level I or level II) were identified using data collected from the trauma information exchange program. Additional data was collected from the Accreditation Council for Graduate Medical Education and the American hospital directory. Results: A total of 788 existing designated PSCs were identified in 2010; coexisting PSC-trauma centers were found in 252 centers (32%) with PSCs coexisting with level I trauma centers in 138 hospitals (17.5%). The remaining 536 PSCs (68%) are based in hospitals without trauma centers. There was a higher proportion of residency training programs including neurology, neurosurgery, and general surgery in coexisting PSC-trauma centers (P < .001). In a proof-of-concept analysis in 1 state, PSCs with level I trauma facilities were found to have the highest rates of thrombolytic administration as compared with PSCs with level II trauma centers and PSCs without trauma facilities (12.8% vs 3.8% vs 4.9%)(P < .0001). Primary stroke centers with level I trauma facilities were also more likely to follow the drip-and-ship paradigm (5.7% vs 1.8% vs 0.9%) (P < .0001). Conclusions: Despite evidence of higher capability among institutions with coexisting PSC-trauma centers, two thirds of PSCs are in hospitals without advanced trauma systems. These findings have implications for establishing stroke systems in the United States.