Tlahualilo de Zaragoza is a city located in the northeastern region of the Mexican state of Durango. It serves as the municipal seat of the Tlahualilo municipio, which borders the state of Coahuila to the east and the municipality of Mapimí to the west. To the south, the area borders the city of Gómez Palacio.
As of 2010, the city had a population of 9,517 residents, while the surrounding municipality had a total population of 22,244. The city is also part of the Comarca Lagunera metropolitan area, which recorded a population of more than 912,000 inhabitants in 2005.