Its county seat is Las Cruces,[2] the second-most populous municipality in New Mexico after Albuquerque, with 111,385 as of the 2020 U.S.

[3] The county is named for Doña Ana Robledo, who died there in 1680 while fleeing the Pueblo Revolt.

Construction of an improved barrier on the border was expedited in 2019 with waivers of environmental and other laws.

The waivers applied to 27 laws, including protection of endangered species, archeological sites, and historic places.

[8] The county contains a number of prominent geographical features, most notably the Mesilla Valley (the flood plain of the Rio Grande) going north to south through the center and the Organ Mountains along the county's eastern edge.

The county also includes one of New Mexico's four large lava fields, the Aden Malpais, and one of the world's largest maare volcanoes, Kilbourne Hole.

As of the 2010 United States census, there were 209,233 people, 75,532 households, and 51,863 families residing in the county.

[16] As of the 2000 United States census,[17] there were 174,682 people, 59,556 households, and 42,939 families residing in the county.

Doña Ana is part of New Mexico's 2nd congressional district, which is currently held by Democrat Gabe Vasquez.

The current state representatives are Jenifer Jones, Micaela Lara Cadena, Raymundo Lara, Angelica Rubio, Nathan Small, Joanne Ferrary, Tara Jaramillo, Doreen Gallegos and Willie Madrid, respectively.

The lawyer stated that pictures taken before and after Slevin's time in jail were key to the trial's outcome.

[28] In August 2013, County Clerk Lynn Ellins announced he would begin granting marriage licenses to same-sex couples.

[29] Several Republican state legislators vowed to file suit against Ellins in a bid to halt the licenses from being issued.