RIO ARRIBA

county, northern New Mexico, U.S., bordered on the north by Colorado. The Continental Divide separates the county's two geographic provinces. Eastern Rio Arriba county is high in the Southern Rocky Mountains, with pine-covered mountains of more than 10,000 feet (3,000 m) in elevation, topped by Trampas Peak (12,175 feet ). Rushing mountain streams feed into the Rio Chama, which empties into the Rio Grande; El Vado Reservoir, Heron Lake, and Abiqui Reservoir lie within the higher elevations. The county includes the San Juan (Pueblo) and Santa Clara (Pueblo) Indian reservations, Chama River Canyon and San Pedro Parks wildernesses, and Heron Lake and El Vado Lake state parks. Western Rio Arriba county is in the Navajo section of the Colorado Plateau, featuring semiarid landscapes and elevations generally descending westward. Arroyos and canyons mark the routes of dry streams through the rough landscape; Navajo Lake, an impoundment of the San Juan River, is the county's northwestern boundary. Also in the western region are the Jicarilla Apache Indian Reservation and Navajo Lake State Park. Carson and Santa Fe national forests cover large sections of the county. Santa Clara pueblo was built early in the 14th century, and the Rio Arriba county region has been continuously inhabited since then. The 1540 expedition of Spanish explorer Francisco Vzquez de Coronado was the first European contact, and a Franciscan missionary who arrived in 1598 became the first European settler. By the mid-18th century the town of Abiqui was a trading centre; Tierra Amarilla, the county seat, also existed before Rio Arriba county was established in 1852. Coal mining and beaver trapping were important to the area's early economic development. By the late 20th century, Rio Arriba county was a popular hunting region; oil and natural-gas extraction, and agriculture (cattle, hay) also are important to the economy. Area 5,858 square miles (15,172 square km). Pop. (1990) 34,365.