Doña Ana County is a
county located in the southern 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, the second-largest in New Mexico. Doña Ana is a Spanish name meaning "Madam Anna" and was probably given in honor of some Spanish matron.