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.

"Chalco" refers to the Chalca tribe, whose territory covered the area around the lake, prior to the Spanish conquest of the Aztec Empire.

This began to change near the end of the 1970s, as hundreds of homesteaders, generally from Mexico City and adjacent urbanized areas, descended upon the region.

The new settlement grew despite the lack of basic infrastructure, such as potable water, sewers, electricity, public transport, medical services and schools.

It was only with the initiation of the Programa Nacional de Solidaridad, in 1988, that the federal government began to install basic services and, ultimately, regularize the tenancy of 77,000 homesteads.