Between 1935 and 1965, the bolero dominated the Latin American musical spectrum. It was first promoted by radio and live programs, then by 78, 46 and 33 RPM records called acetates, then by film and finally by television. It came from Spain to Cuba with characteristics different from those of today and from there it passed to Mexico, which, first by means of acetate, and then through films, to other Latin American countries, especially the Dominican Republic, Venezuela and Puerto Rico. On August 18, 2013, José Fefo Pérez wrote regarding the history of the bolero that it is lost in time "as far back as 1792, but it was not until 1902 when the rhythmic bolero appeared," which began "its transformation." What is a bolero? Ignacio Veles Pareja in "El Diván del Bolero" pointed out in this regard: "It is said that the bolero is a defeatist, pessimistic music and verse that induces melancholy, but this is true in part because there are many kinds of boleros: of exaltation, of searches, reproaches, melancholy, and even songs to cities and religions." Fortunately, the bolero came to stay permanently in Latin America because it has many ways of reproducing itself culturally, through festivals and events such as Valentine's Day and Mother's Day or bolero groups that perform in theaters, clubs, stadiums, concert halls or in open spaces such as squares, streets, and protected avenues. To a greater or lesser degree, the bolero, which has the gift of immortality, is present in all Latin American countries, both in popular settings and in academic halls. We recognize the existence of many exclusions in this monograph, which would require a large research team to work in each country to avoid, with the purpose of investigating each regional reality and thus achieving the clearest possible picture of Latin American bolero music. I have worked alone, tying up loose ends to develop at least one reference that leads to more in-depth research studies.