In Francoist Spain mandates in municipal councils were divided into three pools: in Tercio Familiar only so-called heads of family were entitled to vote, in Tercio Sindical the councillors were chosen in a phased system based on trade unions, and in Tercio de Entidades seats were filled also in a two-step way related to other organizations. Local elections were organized every three years, in each cycle voting for half of the mandates available in every ayuntamiento; from 1948 to 1973 the balloting took place nine times. The system was designed to ensure bureaucratic control of the electoral process and as such it proved largely successful. Electoral campaign was non-confrontational and presented as administrative, not political exercise. Until the 1970s around 45% of adults were entitled to vote, later the figure grew significantly. The turnout is estimated to range from 80% during early Francoism to below 50% in its final stages.