Founded by President George W. Bush after the 9/11 attacks, the National MRC was formed to give volunteers a network to help during a disaster or public health emergency.
From the National MRC website...
The need for the MRC became apparent after the 9/11 terrorist attacks, when thousands of medical and public health professionals, eager to volunteer in support of emergency relief activities, found that there was no organized approach to channel their efforts. Local responders were already overwhelmed and did not have a way to identify and manage these spontaneous volunteers, and many highly skilled people were turned away. As a result, the MRC was established to provide a way to recruit, train, and activate medical and health professionals to respond to community health needs, including disasters and other public health emergencies.
Please check out the Greater Fall River MRC website for more information.