Spanish is the official language, but more than half of the population speaks native languages. About 34 percent speaks Quechua and 25 percent Aymara (mainly in the Cordillera Oriental and southern Altiplano). More than 95 percent of the people are Catholic and about 1 percent Protestant.
Bolivia's population is concentrated mainly in the northern parts of the Altiplano and the basins and valleys of the Cordillera Oriental. The eastern lowlands (with the exception of Santa Cruz and its surroundings), most of the Cordillera Occidental, and the southern parts of the Altiplano are only sparsely populated. Only two of Bolivia's nine departments (17 percent of the total area) have a population density of 16-20 persons per square kilometer (40-50 per square mile), while 59 percent of the total area has a density of less than 3 persons per square kilometer (7.5 per square mile). The average population density for the country as a whole is 6.4 persons per square kilometer (16 per square mile). The portion of the urban population is 49 percent; it was 33.5 percent in 1950.