Santa Teresa is a census-designated place (CDP) in Dona Ana County, New Mexico, United States. It is home to the Santa Teresa Port of Entry and is part of the Las Cruces Metropolitan Statistical Area, although geographically it is considerably closer to El Paso, Texas than to Las Cruces. While the United States Census Bureau has defined Santa Teresa as a CDP, the census definition of the area may not precisely correspond to local understanding of the area with the same name. The population was 4,258 at the 2010 census and 5,044 at the 2020 census. The National Weather Service El Paso Weather Forecast Office that serves extreme western Texas and Southwestern New Mexico states is based in Santa Teresa.

Doña Ana County is located in the southern part of the State of New Mexico, United States. As of the 2020 U.S. Census, its population was 219,561, which makes it the second-most populated county in New Mexico. Its county seat is Las Cruces, the second-most populous municipality in New Mexico after Albuquerque, with 111,385 as of the 2020 U.S. Census.