Valle de Chalco, officially named Valle de Chalco Solidaridad, is a municipality located in the State of Mexico, Mexico, on the eastern outskirts of the metropolitan area of Mexico City. Formerly part of the municipality of Chalco, it was split off as a separate entity in 1994, during the presidency of Salinas de Gortari, under his Programa Nacional de Solidaridad (National Solidarity Program). The municipality lies on the old bed of Lake Chalco, which was substantially drained in the nineteenth century. Technically, the municipal seat is Xico, after a high point of land that once formed an island, and now remains as a small hill within an otherwise monotonous, urban expanse.