In the colonial period Ataco belonged to the administration of the province or municipality over Izalco Sonsonate. As of June 12, 1824 belonged to the municipality of primitive and great department of Sonsonate. Because the law of July 4, 1832 this population was made part of the jurisdiction of the judicial district of Ahuachapán. By legislative decree of February 8, 1855 the town was incorporated in the department of Santa Ana. According to a municipal report dated 20 April 1858, Ataco had a population of 972 inhabitants.