Final answer:
The creation of EMS systems was the most significant governmental action in the 1960s and 1970s to radically change the EMS situation.
Step-by-step explanation:
In the 1960s and 1970s, the most significant governmental action that radically changed the EMS (Emergency Medical Services) situation was the creation of the EMS systems. The EMS systems were established to provide organized and standardized emergency medical care. These systems included the development of paramedic programs, improved pre-hospital care, and enhanced ambulance services.