The sister city pair of El Paso, Texas and Ciudad Juárez, Mexico were first established by the Spaniards in the sixteenth century as El Paso Del Norte. The Franklin Mountains and the Rio Grande provided a north/south continental crossroads for Spanish exploration. Later in 1848, when the Treaty of Guadalupe was drawn up after the Mexico and United States battled over territory, the Rio Grande became an International boundary and split the city into two. With the arrival of the railroad in 1882, the two cities flourished as a frontier community of international importance. Growth in the 1900s were attributed to mining activities in New Mexico, close relations with Fort Bliss as a major military base, use of Elephant Butte Dam as a source for irrigation, and the Border Industrial Program’s growth of maquiladores in Juárez.Today the total population is over 1.9 million with over 500,000 residents in El Paso, 1.3 million in Juárez, and 175,000 in Doña Ana County. There are over 299 Colonias in El Paso County, and 38 in Doña Ana County. The mapping and geospatial data is coordinated through Paso del Norte Mapping for Public Access (PDN MaPA), a tri-state, bi-national municipal planning consortium.