During the 1920s, radio station WKAQ in San Juan, Puerto Rico, played a key role in shaping the island’s national identity through its musical programming. Inaugurated in 1922 with a broadcast from the Teatro Rialto, WKAQ was among the first radio stations in Latin America and quickly became a fixture of musical life on the island. Influential figures such as Joaquín Burset, the station’s artistic director, and the Figueroa-Sanabia family curated musical tastes by hosting frequent, diverse radio concerts featuring the station’s studio orchestra and other popular ensembles. These performances included works by local Puerto Rican composers, as well as classical and U.S. popular music. Station host Joaquín Agusty and Burset emphasized that all musical broadcasts should include at least one piece in the style of a danza, Puerto Rico’s national music genre. Applying a historical-ethnographic lens to contemporaneous census data, U.S. Department of Commerce trade reports, printed programs, and historical newspapers, this paper traces WKAQ’s early years, revealing the station’s financial structure, reach, and programming. I argue that by consistently featuring local genres and musicians, WKAQ helped shape Puerto Rican national identity and consolidate a distinct Puerto Rican musical canon. The experimental nature of radio in the 1920s, combined with Puerto Rico’s cultural self-assertion under U.S. colonialism, positions this case study to provide valuable insight into how emerging mass media technologies influenced nation-building, popular tastes, and canon formation in the early twentieth century.