Puerto Rico is the easternmost and smallest of the Greater Antilles, bordered by the Atlantic Ocean to the north and the Caribbean Basin to the south.
Neither a state nor independent, the island has been a US territory since 1898.
Everyone born on the island is an American citizen and holds a US passport. However, residents cannot vote in US presidential elections, unless they are registered to vote in one of the 50 states.
Puerto Rican culture is a blend of Amerindian Taino, Spanish and African influences with Spanish being the island's first language.
Tourism is an important money-earner and the island attracts millions of visitors each year. But crippling public debt, poverty and high unemployment have seen many of the islanders leave for the US mainland.
Head of State: President Donald Trump
Governor (outgoing): Ricardo Rosselló
Ricardo Rosselló was sworn in in January 2017 after winning the governor's race, promising to push for statehood as the territory faced a deep economic crisis.
He proposed several measures aimed at alleviating the crisis, including a a referendum on statehood or independence, but the subsequent vote for statehood saw only 23% of voters take part.
Mr Rosselló's term in office came to an abrupt end in the summer of 2019, when he resigned in the wake of a group text message scandal involving offensive comments.
The commonwealth constitution is modelled on that of the United States, with a governor elected for a four-year term and a bicameral legislature.
Broadcasting is regulated by the US Federal Communications Commission (FCC).
Home-grown comedies, talk shows and Spanish-language soaps are staple fare on local TV stations. The multichannel offerings of cable TV are widely available.
News and talk and Spanish-language pop music are among the most popular radio formats.
There were 2.6 million internet users by June 2014 Internetworldstats.com).
Some key dates in the history of Puerto Rico:
1493 - Christopher Columbus claims the island for Spain on his second voyage to the Americas. Spanish explorer Juan Ponce de Leon establishes the first settlement in 1508.
1500s - Indigenous Amerindian Taino population is virtually wiped out by disease and new settlers. African slave labour is imported.
1868 - A popular uprising against Spanish rule is suppressed but becomes a symbol of the independence struggle.
1898 - Spain cedes Puerto Rico to the US at the end of the Spanish-American War.
1900 - US Congress establishes a civil government under the Foraker Act but maintains strict control over island affairs. Puerto Ricans are granted US citizenship in 1917 under the Jones Act.
1940s - Puerto Rico gains partial self-rule with popularly elected governors.
1952 - Puerto Rico becomes a self-governing commonwealth of the United States. Under US administration, it experiences growth but nationalist sentiment is still present.
1960-70s - Violent separatism - A series of bombings and killings in the 1970s and 1980s are blamed on pro-independence group, the Macheteros, or Cane Cutters.
1998 - Puerto Ricans back continued commonwealth status in a referendum.
2003 - The US government stops military training on the offshore island of Vieques after protests.
2006 - The expiry of a federal tax break for US corporations in place since 1976 triggers economic recession.
2012 - Puerto Ricans vote for US statehood for the first time in a non-binding referendum on the island's status.
2017 - The territory declares bankruptcy - the largest ever for a US local government. In a non-binding referendum, it votes again to become a US state although only 23% of voters take part.