From the 19th to 20th century, migrations from rural areas into Guadalajara, along with the Mexican government's cultural promotion gradually re-labeled it as "son" style, with its alternative name of "mariachi" becoming used for the 'urban' form. Modifications of the music include influences from other music such as polkas and waltzes, the addition of trumpets and the use of charro outfits by mariachi musicians. The musical style began to take on national prominence in the first half of the 20th century, with its promotion at presidential inaugurations and on the radio in the 1920s. In 2011, UNESCO recognized mariachi as an Intangible Cultural Heritage, joining six other entries on the Mexican list of that category.