seats elected by the usos y costumbres, using first-past-the-post voting. A voter can only vote in one of either the normal constituencies or special constituencies. The Chamber of Senators (Cámara de Senadores) has 36 members, four from each the country's nine departments, which are also elected using closed party-lists, using the D'Hondt method. Both the senate, and the proportional part of the Chamber of Deputies is elected based on the vote for the presidential candidates, while the deputies from the single-member districts are elected using separate votes. Party lists are required to alternate between men and women, while candidates in single-member districts are required to have an alternate, of the opposite sex. At least 50% of the single-member deputies are required to be women History of elections in Bolivia Indirect elections, 1825-50 Elections were conducted in the early Republican period using multiple levels of electors, each of which would elect members of the next higher level, culminating in the president. Direct elections with restricted suffrage, 1839 and 1850-1938 In the elections of 1839, however, the president was elected by a majority of all voters. This system became the norm beginning in 1850. Voting requirements included a minimum property or income or service in one of the professions, and forbid all those "in domestic service" from voting. Indigenous peoples were effectively excluded from the franchise. Expanding electorate, 1938-1951 Under the Constitution of 1938, property restrictions on voting were removed however the vote was still restricted to those who were male, literate, and of age. Elections were held in 1940 and 1951, and saw a dramatic expansion of the electorate. Universal suffrage and interruptions in democracy, 1952-79 Shortly after coming to power through the , the National Revolutionary Movement instituted universal suffrage, ending literacy requirements and racial restrictions which had massively reduced the Bolivian electorate up to that time. General elections were held in 1956, 1960, and 1964; and purely legislative elections were held in 1958 and 1962. Democracy was interrupted in 1964 by René Barrientos Ortuño, who proceeded to hold and win an election in 1966 and to convoke the Constituent Assembly of 1966-67 to rewrite the Constitution of Bolivia. Following Barrientos' death in 1969, democracy was further interrupted by military rule until 1979, including the eight-year dictatorship of Hugo Bánzer Suarez. Democratic transition and final dictatorship, 1979-82 In a chaotic period of transition marked by numerous coups d'état, three elections