Fort Selden was a United States Army post, occupying the area in what is now Radium Springs, New Mexico. The site was long a campground along the El Camino Real de Tierra Adentro. It was the site of a Confederate Army camp in 1861. The U.S. Army established Fort Selden in 1865 for the purpose of protecting westward settlers from Native American raids, but the post fell into disrepair after the American Civil War. It was ultimately abandoned in 1891, due in large part to the decision to expand Fort Bliss and the lack of any expenditures for repair of the facility.

Radium Springs is a census-designated place (CDP) in Doña Ana County, New Mexico, United States. The population was 1,699 at the 2010 census. It is part of the Las Cruces Metropolitan Statistical Area.