A border blaster is a broadcast station that, though not licensed as an external service, is, in practice, used to target another country. The term "border blaster" is of North American origin, and usually associated with Mexican AM stations whose broadcast areas cover large parts of the United States, and United States border AM stations covering large parts of Canada. Conceptually similar European broadcasting included some pre-World War II broadcasting towards the United Kingdom, "radio périphérique" around France and the U.S. government-funded station Radio Free Europe, targeting eastern Europe. With broadcasting signals far more powerful than those of U.S. stations, the Mexican border blasters could be heard over large areas of the U.S. from the 1940s to the 1970s, often to the great irritation of American radio stations, whose signals could be overpowered by their Mexican counterparts. These are also sometimes referred to as X stations for their call letters: Mexico assigns callsigns beginning with XE or XH to broadcast stations. On November 9, 1972, in Washington, D.C., the United States and Mexico signed an "Agreement Concerning Frequency Modulation Broadcasting in the 87.5 to 108 MHz Band". Since then, in the FM band power levels and frequency assignments have been set by mutual agreement between the two countries. AM radio border blasters still exist, though they are largely ignored due to the decline of AM radio in the U.S. and in Mexico. There are several such stations licensed by Mexico's Secretariat of Communications and Transportation using transmitters with an effective radiated power similar to those of major licensed commercial stations located within the U.S. Background In contrast to pirate radio stations which broadcast illegally, border blasters are generally licensed by the government upon whose soil they are located. Pirate radio stations are freebooters from offshore, outside the territorial waters of the nation they target, or ones that are illegally operating in defiance of national law within its sovereign territory. They also contrast with shortwave radio broadcasters, which operate on frequencies expressly designated for international broadcasts, whereas border blasters use frequencies designated for domestic broadcasts. Mexico to U.S. In Mexico and the US, while the federal government of the US did not particularly like them, the stations were allowed to flourish. W. Lee O'Daniel used a border blaster in his successful campaign for governor of Texas. The US, unlike the UK, has never required a license to listen to broadcast radio