The Comarca Lagunera or La Comarca de la Laguna ("region of lagoons") is a region of northern Mexico occupying large portions of the states of Durango and Coahuila, with rich soils produced by periodic flooding of the Nazas and Aguanaval rivers. Neither river drains into either the Pacific Ocean or the Gulf of Mexico, but rather they created a series of inland lakes. The region was developed for large-scale irrigated cotton agriculture. During the Mexican Revolution, the region was the site of fierce fighting. Following the military phase of the Revolution, the region was part of the agrarian reform under President Lázaro Cárdenas. The dam named for Cárdenas now controls flooding of the rivers, but the groundwater resources are no longer recharged as a result. It is the 8th largest metropo