Puerto Rico's population is Spanish speaking (most also speak English) and largely of mixed white, black, and Indian origins. Whites include Spanish, French, Italian, and Portuguese ethnicities. Blacks arrived from Africa as slaves in the 16th century. A small group traces their descent from Arawak Indians who married Spanish settlers, but there is no longer a full-blooded Indian native population on the island. Of its 3,528,145 (1990) inhabitants, 241,323 (about 7%) were born in the United States or in U.S. outlying areas, or of American parents abroad, and 79,804 (2.3%) were foreign born. Some 55% of the foreign born are not naturalized U.S. citizens. Beginning in the 1960s and 1970s, Puerto Rico became a recipient, not only of second- and third-generation Puerto Ricans returning from the United States, but also of a growing number of immigrants from the Caribbean, particularly from Cuba (after the Cuban Revolution) and the Dominican Republic. The latter group, with a population of 40,000 (1990), is considered to be seriously undercounted.

Puerto Rico has 78 municipios, or political units. The smallest municipio in area is Cataño, and the largest is Arecibo. The most populous is San Juan; the least populous is the island-municipio of Culebra. Puerto Rico has five metropolitan areas: San Juan -Caguas, Ponce, Mayagüez, Arecibo, and Aguadilla. The consolidated metropolitan area of San Juan and Caguas has nearly 2 million people. An overwhelming majority of the population are Christian, mostly Roman Catholic.

According to the first U.S. population census of Puerto Rico, taken in 1899, there was a population of 953,000. By the end of World War II the population had increased to 2 million and by 1975 to about 3 million. By 2000, the population was more than 3.8 million. Had Puerto Ricans not migrated in heavy numbers to the United States after World War II, the current island population would probably exceed 6 million.

During the first four decades of the 20th century, birthrates in Puerto Rico averaged about 40 per thousand, a very high rate, but death rates were also high, ranging from a high of 28 per thousand in 1900 to a minimum of 20 per thousand in 1935. As a result the population increase averaged about 1.5% per year during this period. Birthrates increased after World War II and remained at over 30 per thousand until the mid-1960s. Death rates, however, decreased rapidly, from 20 per thousand between 1930 and 1935 to less than 7 per thousand since the 1960s. As a consequence the natural increase of the Puerto Rican population remained high until the 1970s, after which it eventually dropped to less than 1% per year in the 1990s. The Puerto Rican population has been transformed from a young population, with a median age of less than 18.5 years between 1900 and 1960 to 27.3 years in 1990.

A dramatic rural-to-urban migration characterized the population dynamics of the post -World War II era. While only 30% of the Puerto Rican population lived in urban areas in 1940, more than 70% were considered urban in 1990. The geographic mobility of the Puerto Rican population is exemplified not only by the migration to the United States but also by the internal redistribution of the population. According to the 1990 census, 53% of the population now live in a municipio different from the one in which they were born.

Education. Puerto Rico's Constitution guarantees free schooling up to the 12th grade. The Department of Education is headed by a secretary named by the governor and confirmed by the Senate. In addition to the public school system, Puerto Rico has private schools at the precollege level, mostly owned and operated by Roman Catholic and some Protestant churches; there are also secular private schools.

The University of Puerto Rico is the public land-grant institution. As the largest system it consists of three major campuses - the Río Piedras campus and the medical campus, both in San Juan, and the Mayagüez campus, which houses the school of engineering. The public regional college system, also part of the University of Puerto Rico, includes 4-year university colleges at Aguadilla, Arecibo, Bayamón, Humacao, Ponce, and Cayey, as well as regional 2-year colleges at Carolina and Utuado.

Puerto Rico also has several private universities. The largest and oldest of these is the Inter-American University of Puerto Rico, with its original campus, founded in 1912, located in San Germán; constituent campuses are in Hato Rey, Bayamón, and Arecibo; and regional campuses are in Aguadilla, Barranquitas, Guayama, Fajardo, and Ponce. Pontifical Catholic University of Puerto Rico (1948) in Ponce, the University of the Sacred Heart (1935) in Santurce, and Bayamón Central University (1970) are Catholic universities.

Culture and Historical Sites. Puerto Rico's Hispanic history goes back to Columbus's arrival in 1493. Historical sites of interest include old San Juan, which is rich in old Spanish architecture and has narrow cobblestone streets and a pleasant Old World atmosphere. Among the more outstanding buildings are the San Felipe del Morro and the San Cristóbal fortresses, the San José Church, and the Governor's Mansion. Some historical San Juan museums are the Arsenal de la Marina, Museo de Casa Blanca, San Gerónimo Fortress, El Morro Fortress, the Palacio Santa Catalina (Governor's Mansion), and the Museo Pablo Casals, with mementos of the famed Spanish cellist who organized a now world famous music festival in Puerto Rico. Other museums include the Art and Anthropology Museum at the University of Puerto Rico, in Río Piedras; the Museum of Religious Art in the Porta Coeli Chapel in San Germán; and the Museum of Art in Ponce. Archaeological museums of Indian artifacts in San Juan, Caguana, and Utuado (at the Indian Ceremonial Ball Park) offer evidence of Puerto Rico's pre-Columbian heritage.

Communications. Television started in Puerto Rico on Mar. 28, 1954; the first transmission was by WKAQ, Channel 2, and WAPA, Channel 4, followed during the same year. In 1958 the government television station (WIPR) began operations. The first color transmission as well as the first television satellite reception - the U.S. baseball World Series - took place in 1968. Eighteen television stations were in operation in 1996, and there are several cable companies on the island. The AM and/or FM radio stations include public as well as commercial and religious stations. Puerto Rico has three main daily newspapers: El Nuevo Día and El Vocero, in Spanish, and the San Juan Star, in English. Weekly national newspapers are Claridad and El Diario.