Regionalized trauma care has been widely implemented in the United States, with field triage by emergency medical services (EMS) playing an important role in identifying seriously injured patients for transport to major trauma centers. In this study we estimated hospital-level differences in the adjusted cost of acute care for injured patients transported by 94 EMS agencies to 122 hospitals in 7 regions, overall and by injury severity. Among 301,214 patients, the average adjusted per episode cost of care was $5,590 higher in a level 1 trauma center than in a nontrauma hospital. We found hospital-level differences in cost among patients with minor, moderate, and serious injuries. Of the 248,342 low-risk patients-those who did not meet field triage guidelines for transport to trauma centers-85,155 (34.3 percent) were still transported to major trauma centers, accounting for up to 40 percent of acute injury costs. Adhering to field triage guidelines that minimize the overtriage of low-risk injured patients to major trauma centers could save up to $136.7 million annually in the seven regions we studied.