the municipios were defined legally by the Commonwealth during the late 1940s. Since then, the Commonwealth established two new municipios. In 1971, Florida was carved out of Barcelona and, in 1973, Canóvanas was separated from Loíza. In addition, in 1951, San Juan Municipio annexed Río Piedras Municipio. Only the Commonwealth legislature can create new municipios and alter the boundaries of existing ones. There have been unofficial discussions within the Government of Puerto Rico regarding the desirability of revising municipio and other legal boundaries to avoid the confusion related to those lines that pass through new housing developments and even individual houses, but no action has been taken to change these situations.
The municipios are subdivided into barrios, which the Census Bureau treats as MCDs. One barrio in each municipio (except Florida, Ponce, and San Juan) is identified as the barrio-pueblo, the area that represented the seat of government at the time the Commonwealth formalized the municipio and barrio boundaries in the late 1940s. Until the 1990 census, the barrio-pueblo—also referred to as the pueblo barrio or barrio urbano in some legal documents—was simply called a pueblo; because this word is translated as town, the decennial censuses also treated the pueblo as a place until the 1980 census. Some (but not all) barrios and barrios-pueblo in 23 municipios have been further subdivided into subbarrios, which the Census Bureau treats as sub-MCDs; these, too, were formalized in the 1940s. Subbarrios completely cover the area within each barrio that has subbarrios; that is, subbarrios nest within barrios. The barrios and subbarrios do not have their own governments; rather, they are areas from which members of both the Puerto Rico legislature and the municipio assemblies are elected. For this purpose, barrios and subbarrios may comprise single- or multi-member districts, or may be grouped into legislative districts. A municipio government may amend the limits of its barrios and subbarrios legally, provided that it reports the changes to the Puerto Rico Planning Board.
For many decades, the decennial censuses also recognized entities called ciudades, which contained the most urban barrios of Ponce and San Juan,
Puerto Rico and the Outlying Areas7-33
