Country music different genres and subgenres, depending on where they originated, and in what regions they are popular. One specific song style, the ranchera, found its origins in the Mexican countryside and was first popularized with mariachi, and has since also become popular with banda, norteño, Duranguense and other regional Mexican styles. The corrido, a different song style with a similar history, is also performed in many different regional styles. Other song styles performed in regional Mexican music include ballads, cumbias, boleros, among others. American country music is also popular in Mexico, but most prominently in the northern regions of the country,
Mariachi problems recruiting mariachi instructors as many of these do not have required teaching credentials. For this reason, schools often hire trained musicians from outside the mariachi tradition. Many traditional mariachis are concerned that standardization will lead to fossilization and restrict improvisation. Other innovations in the United States have been the incorporation of styles of artists such as Elvis Presley, Freddy Fender and Glenn Miller, as well as the heavy-metal Mariachi band Metalachi. Another is the encouragement of female mariachis including all-female Mariachi groups such as Mariachi Mujer 2000 and Mariachi Divas de Cindy Shea. Mariachi Mujer has performed with Mexican