Doña Ana County is a county located in the southcentral part of the U.S. state of New Mexico. As of the 2010 census, the population was 209,233, which makes it the second most populated county in New Mexico. Its county seat is Las Cruces, also the largest city in the county and second-largest in New Mexico. Smaller towns in the county include Mesilla, Doña Ana, Hatch, and Organ. Doña Ana is pronounced Doñana. It borders between western Texas and Mexico's Chihuahua state. - Source: Wikipedia