The constituency was created as per the Political Reform Act 1977 and was first contested in the 1977 general election. The Act provided for the provinces of Spain to be established as multi-member districts in the Congress of Deputies, with this regulation being maintained under the Spanish Constitution of 1978. Additionally, the Constitution requires for any modification of the provincial limits to be approved under an organic law, needing an absolute majority in the Cortes Generales.
Voting is on the basis of universal suffrage, which comprises all nationals over eighteen and in full enjoyment of their political rights. The only exception was in 1977, when this was limited to nationals over twenty-one and in full enjoyment of their political and civil rights. Amendments to the electoral law in 2011 required for Spaniards abroad to apply for voting before being permitted to vote, a system known as "begged" or expat vote (Spanish: Voto rogado). 348 seats are elected using the D'Hondt method and a closed list proportional representation, with a threshold of 3 percent of valid votes—which includes blank ballots—being applied in each constituency. Parties not reaching the threshold are not taken into consideration for seat distribution. Additionally, the use of the D'Hondt method may result in an effective threshold over three percent, depending on the district magnitude. Each provincial constituency is entitled to an initial minimum of two seats, with the remaining 248 allocated among the constituencies in proportion to their populations. Ceuta and Melilla are allocated the two remaining seats, which are elected using plurality voting.
The electoral law provides that parties, federations, coalitions and groupings of electors are allowed to present lists of candidates. However, groupings of electors are required to secure the signature of at least 1 percent of the electors registered in the constituency for which they are seeking election—0.1 percent and, at least, the signature of 500 electors, until 1985—. Also since 2011, parties, federations or coalitions who have not obtained a mandate in either House of Parliament at the preceding election are required to secure the signature of at least 0.1 percent of the electors registered in the constituency for which they are seeking election. Electors are barred from signing for more than one list of candidates. Concurrently, parties and federations intending to enter in coalition to take part jointly at an election are required to inform the relevant Electoral Commission within ten days of the election being called.