Several organizations in the United States are involved in setting standards for pre-hospital emergency care provided by EMTs and paramedics. Here are a few key ones:

Care in Transit, and Transfer to Definitive Care.
National Highway Traffic Safety Administration (NHTSA): NHTSA plays a significant role in developing evidence-based guidelines for pre-hospital care. They work in partnership with professional organizations to create model prehospital care protocol.
National Association of EMS Physicians (NAEMSP): NAEMSP is involved in the development, implementation, and evaluation of evidence-based guidelines through the Prehospital Guidelines Consortium.
National Registry of Emergency Medical Technicians (NREMT): NREMT collaborates with other organizations to identify and appraise guidelines for pre-hospital care.
Federal Interagency Committee on Emergency Medical Services (FICEMS): FICEMS supports the development, implementation, and evaluation of evidence-based guidelines according to the National Prehospital EBG Model Process.