Pecos National Historic Park is in San Miguel and Santa Fe Counties, New Mexico. The park, operated by the National Park Service, encompasses thousands of acres of landscape infused with historical elements from prehistoric archaeological ruins to 19th-century ranches, to a battlefield of the American Civil War. Its largest single feature is Pecos Pueblo, a Native American community abandoned in historic times. First a state monument in 1935, it was made Pecos National Monument in 1965, and greatly enlarged and renamed in 1990. Two sites within the park, the pueblo and the Glorieta Pass Battlefield, are National Historic Landmarks