Electoral region (Bulgaria)
The territory of Bulgaria is divided into 31 electoral regions () roughly corresponding to the 28 provinces (, "Oblasti") of Bulgaria. National Assembly Seats. Each electoral region nominates a predefined number of seats to the National Assembly of Bulgaria, according to census data for the population of each region. Since 1991, a proportional electoral system was used, with the exception of 2009 parliamentary election. For 2013 parliamentary election the previous proportional electoral system was restored. In 2009 a mixed system with both simple majority and proportional distribution was introduced. Each one-seat region corresponds to the traditional multi-seat  regions. Because of the big diversity of population between regions, this one-seat distribution came into contradiction to article 10 of the Constitution of Bulgaria, stating that elections are to be conducted with equal right to vote. An appeal of this contradiction was brought to the Constitutional Court of Bulgaria, which failed to make a decision, voting 6 to 6. The number of proportional seats for each electoral region was to be reduced by one to allow 31 simple majority seats to be added, while keeping the total number of seats to 240. This led to another controversy, as the  seats for some of the regions were reduced by 1, others by 2 and some kept the same number of seats, effectively increasing the total number of seats for the region, including the simple majority seat. Electoral regions. Most electoral regions correspond to the 28 provinces of Bulgaria, except for the two most populous provinces, which are further subdivided. Plovdiv Province is divided into Electoral region 16, corresponding to Plovdiv municipality and Electoral region 17, covering all other municipalities. Sofia City is divided into Electoral regions 23, 24 and 25. Sofia Province which is distinct from Sofia City is represented  by Electoral region 26. Administrative Regions of Sofia. The City of Sofia is divided into 24 Administrative regions. Electoral regions 23, 24 and 25 cover 8 Administrative regions each.