Aetolia-Acarnania is one of the regional units of Greece. It is part of the region of West Greece. It is located in the western part of Greece; the regional unit is a combination of the geographic regions Aetolia and Acarnania. Its capital is Missolonghi for historical reasons, with its biggest city and economic centre at Agrinio. The area is now connected with the Peloponnese peninsula via the Rio-Antirio Bridge. The surrounding regional units take in Arta in Epirus, a narrow length bordering Karditsa of Thessaly, Evrytania to the northeast, and Phocis to the east. This is the largest regional unit in Greece.
Aetolia and Acarnania became a prefecture and merged to form Aetolia-Acarnania after the Greek War of Independence in the late-1820s; the prefecture included Evrytania at the time, and it ranked second largest in Greece. Evrytania separated from the prefecture in 1948. In the 20th century, ferry services between Rio and the Peloponnese began. and in the 1950s and the 1960s ferry services began to incorporate vehicles. Following World War II and the Greek Civil War a number of buildings needed to be repaired.
A drawbridge linking the island of Lefkada began in the 1960s. The prefecture's first reservoir, the Acheloos Dam over the Acheloos was under construction in 1967 and completed in the early-1970s delivering water and hydro to western part of Greece, villages were relocated at the time. Two more dams were added, the Stratos Hydroelectric Dam in the 1980s and another in the late-1980s.