(often shortened to CB radio) is, in many countries, a system of short-distance radio communications between individuals on a selection of 40 channels within the 27-MHz (11 m) band. The CB radio service is distinct from FRS, GMRS, MURS, or amateur ("ham") radio. In many countries, CB does not require a license and, unlike amateur radio, it may be used for business as well as personal communications. Like many other two-way radio services, Citizens' Band channels are shared by many users. Only one station may transmit at a time. Other stations must listen and wait for the shared channel to be available.
Following the 1973 oil crisis, the U.S. government imposed a nationwide 55 mph speed limit, and fuel shortages and rationing were widespread. CB radio was often used, especially by truckers, to locate service stations with a supply of gasoline, to notify other drivers of speed traps, and to organize blockades and convoys in a 1974 strike protesting the new speed limit and other trucking regulations. The prominent use of CB radios in 1970s-era films such as Smokey and the Bandit (1977), Convoy (1978), television shows like Movin' On (debuted 1974), The Dukes of Hazzard (debuted 1979), and popular novelty songs such as C.W. McCall's Convoy (1976) helped establish CB radio as a nationwide craze in the USA in the mid- to late-1970s.