For a century, Puerto Casado was the capital of quebracho, the hardwood tree prized for its tannin: the Carlos Casado company's tannin-extract factory, now idle, dominates the riverbank with its warehouses and the houses of its employees and owners. A narrow-gauge railway ran inland from here, carrying the Mennonite pioneers and the soldiers of the Chaco War. Today it's a quiet town of fishermen and ranchers, where the industrial heritage, the river and Cerro Galván hill to the south tell stories of another era.

In 1886 Carlos Casado del Alisal acquired millions of hectares of the Chaco and set up a quebracho-extract factory which, according to the company itself, was the first in the Americas; it ran until 1996. The town was founded on August 25, 1889 under the name Ángeles Custodios. In 1931 José Félix Estigarribia took command of an infantry division here, and the port and railway were key to moving troops during the Chaco War.