San Mateo is a census-designated place in Cibola County, New Mexico, United States. As of the 2020 census, San Mateo had a population of 139.
The community has a Catholic church, a Baptist church, a Morada, a cemetery, a Volunteer Fire Department(McKinley County funded) and an old abandoned elementary school. It is also coined "the Uranium Capital of the World".
San Mateo is from Grants. It overlooks Mount Taylor.