Piedras Negras DistrictPiedras Negras is a district of the Mora canton, in the San José province of Costa Rica.GeographyPiedras Negras has an area of km2 and an elevation of metres.DemographicsFor the 2011 census, Piedras Negras had a population of inhabitants.TransportationRoad transportationThe district is covered by the following road routes: National Route 136 National Route 316