Paraguay is divided into 17 departments, which are subdivided into districts, which, in turn, comprise municipalities (the minimum requirement for a municipality is 3,000 persons) and rural districts ( partidos ). A governor, elected by popular vote, runs each department. Municipal government is exercised through a municipal board, chosen by direct election, and an executive department. In the principal cities and capitals, the executive department is headed by a mayor appointed by the minister of the interior; in other localities, the mayor is appointed by the presidents of the municipal boards. Police chiefs are appointed by the central government.