FACTBOX: Key facts about Spain

(Reuters) - Spain holds a parliamentary election on Sunday after a close campaign marked increasingly by a darkening economic outlook and the end of a housing boom.

Here are some key facts about Spain:

GEOGRAPHY: Area 504,782 sq km (194,900 sq miles) including the Balearic and Canary Islands and the enclaves of Ceuta and Melilla in North Africa.

-- Spain occupies the bulk of the Iberian peninsula, which it shares with Portugal to the west. It is bounded to the north by the Atlantic Ocean and France, to the east by the Mediterranean, and to the south by the Straits of Gibraltar. On its southern tip is Gibraltar, a British colony.

-- Spain is divided into 17 autonomous regions.

POPULATION: 45.1 million (2007).

LANGUAGE: The main official language is Castilian Spanish, while 30 percent also speak one of the three official regional languages of Catalonia, the Basque Country and Galicia.

CAPITAL: Madrid (2003 population: 5.1 million).

RELIGION: The majority of Spaniards are Catholic (95.2 percent). There is a small Muslim population (1.2 percent)

ECONOMY: Spain ran the euro zone's second largest budget surplus in 2007, equivalent to 2.2 percent of GDP, and has built up a war chest that the government may need to use to fight an economic slowdown.

-- The surplus, of 23.4 billion euros ($34.5 billion), was the third in a row, after three decades of deficits.

-- Spain may use that war chest to try to keep growth around 3 percent, and given expectations that it will run a budget surplus equal to at least 1.15 percent of GDP in 2008. Its public debt stood at 36.2 percent of GDP in 2007.

-- Economic growth was 3.8 percent in 2007, slightly down on 2006. Growth in each of the last three quarters was down on the previous year.

-- Many Spaniards fear there will be an economic crisis. Retail sales and industrial production have both fallen as households put off purchases.

SOME RECENT HISTORY: The Spanish civil war ended in 1939, ushering in an era of right-wing dictatorship until General Francisco Franco's death in 1975.

-- The Basque separatist group ETA launched its violent campaign for independence in 1968 in response to Franco's repression of Basque culture and language.

-- ETA has killed more than 800 people, despite the granting of broad powers of self-rule to the Basque region, and the issue of how to deal with it remains the most poisonous issue in Spanish politics.

-- Spain held its first democratic elections in more than four decades in 1977. A year later, the constitution was signed. The Socialist Party under Felipe Gonzalez scored a landslide victory in 1982 and won three more general elections after that.

-- In 1996, Jose Maria Aznar's centre-right Popular Party wrested power from the Socialists, who were beset by corruption scandals.

-- The Socialists under Jose Luis Rodriguez Zapatero won a surprise election victory in 2004 after the PP government mistakenly blamed ETA for coordinated Islamist bomb attacks on Madrid commuter trains.

Sources: Reuters/New Internationalist World Guide

(Writing by David Cutler, London Editorial Reference Unit; Editing by Kevin Liffey)