RACES, administered by local/county/state Emergency Management agencies, with guidance from the Federal Emergency Management Agency (FEMA), is part of the Amateur Radio Service that provides radio communications for civil-preparedness purposes only, during periods of local, regional or national civil emergencies.
These emergencies are not limited to war-related activities, but can include natural disasters such as fires, floods, and earthquakes. Amateurs operating in a local RACES organization must be officially enrolled in the local civil-preparedness group.
While RACES was originally based on potential use for wartime, it has evolved over the years, as has the meaning of civil defense, to encompass all types of emergencies.
ARES and RACES
Although RACES and ARES are separate entities, the ARRL advocates dual membership and cooperative efforts between both groups whenever possible. An ARES group whose members are all enrolled in and certified by RACES operate in an emergency with great flexibility. Using the same operators and the same frequencies, an ARES group also enrolled as RACES can "switch hats" form ARES to RACES to meet the requirements of the situation as it develops.
Taken from the ARES Field Resources Manual, published by the ARRL.