Municipalities are subdivided into wards or barrios, and those into sectors. Each municipality has a mayor and a municipal legislature elected for a four-year term. The municipality of San Juan (previously called "town"), was founded first, in 1521, San Germán in 1570, Coamo in 1579, Arecibo in 1614, Aguada in 1692 and Ponce in 1692. An increase of settlement saw the founding of 30 municipalities in the 18th century and 34 in the 19th. Six were founded in the 20th century; the last was Florida in 1971.