Piedras Negras Municipality is one of the 38 municipalities of Coahuila, in north-eastern Mexico. The municipal seat lies at Piedras Negras. The municipality covers an area of 914.2 km<sup>2</sup> and is located on the international border between Mexico and the USA, here formed by the RÃÂo Bravo del Norte (Rio Grande), adjacent to the U.S. state of Texas.
As of 2010, the municipality had a total population of 152,806.
The largest localities (cities, towns, and villages) are: