Objective: Timely triage and appropriate destination decision making for injured patients are central challenges faced by emergency medical services (EMS) systems. In 2010, North Carolina (NC) adopted a statewide Trauma Triage and Destination Plan (TTDP) based on the CDC's Field Triage Guidelines to better address these challenges. We sought to characterize the implementation of these guidelines by quantifying their effect on multiple metrics of patient care. Methods: We employed a retrospective pre-post study design utilizing a statewide EMS medical record database. We assessed several metrics of patient care—including changes in destination choice, appropriateness of EMS destination, transit time to first hospital, transit time to definitive care, and others—in a six-month period in the year before and after the implementation of the guidelines. Results: We evaluated a total of 190,307 EMS encounters pre- (n = 93,927) and post-implementation (n = 96,380). Among all patients, there was not a significant difference in the percentage transported to a community hospital or Level I, II, or III trauma center as their first destination. Among those patients meeting TTDP guidelines for transport to a trauma center, the number transported to a Level I or II trauma center decreased 1.0% from 30.6% (n = 2,911) to 29.6% (n = 2,954) (95% CI: −0.2%, 2.2%). Those transported to a Level I trauma center decreased 0.4% from 21.2% to 20.8% in the post-period (95% CI: −0.7%, 1.5%). There were also no significant changes in EMS scene times (14.0 pre-, 14.1 post-) and transport times (12.9 pre-, 13.0 post-). While scene distance from a Level I trauma center showed a decreased likelihood of transport to that center, there was an overall post-implementation increase of 2.5% from 18.0% to 20.5% (95% CI: −3.6%, −1.3%) in transport to a Level I trauma center among patients meeting anatomic criteria across all distance ranges. Conclusions: We found that implementation of region-specific destination plans based on the Field Triage Guidelines had little effect on selected hospital destination, scene times, transport times, and other metrics of EMS decision making and effectiveness. We suspect this is due to delays in information dissemination and adoption by field providers.