Terrell County is in the Big Bend area of southwestern Texas, bordered on the south by Mexico, on the east by Val Verde and Crockett counties, on the north by Pecos County, and on the west by both Pecos and Brewster counties. The center point of the county is at 30°15' north latitude and 102°03' west longitude. Sanderson, the county seat, is about halfway between San Antonio and El Paso. The county was named for Alexander Watkins Terrell. Terrell County comprises 2,357 square miles of rocky terrain with elevations ranging from 1,300 to 4,000 feet above sea level. The soils are of limestone origin. Most of the county is situated in the Stockton Plateau, a part of the Western Mountain region. The eastern and northeastern parts of the county consist of gently rolling to level plains. In the western part the land slopes much more and the rolling terrain becomes mountainous, with narrow canyons and valleys. In the southern portion, the rocky lands near the Rio Grande are cut by deep canyons that carry floodwater into the muddy Rio Grande, which defines the county's southern boundary. Deep canyons also traverse the eastern plains and empty into the Pecos river, which runs along the county's northeastern border. While the Pecos and Rio Grande are the principal waterways in the county, their accessibility to livestock is severely limited in many places by steep cliffs and deep canyons. There are a number of springs in the county, including Independence, King, Myers, Cedar and Geddes springs. Generally, windmill wells and tanks provide water for livestock. With an annual rainfall of only about fifteen inches, Terrell County lands generally are suited only for the grazing of livestock. Less than 1 percent of land in the area is prime farmland. The only trees of any size, primarily walnut and hackberry, grow along the dry creekbeds. The draws and creekbeds often are choked with underbrush that provides good browse for sheep and goats. The hills grow varieties of grama grass, sotol, juniper, lechuguilla, and various varieties of brush. Out on the grassy flats grow the ojasen (tarbush or greasewood), the gobernadora (creosote bush), and the ubiquitous mesquite. A number of plants that grow wild in the area are gathered for medicinal and other purposes. Ojasen and gobernadora leaves are used by many of the local people as medicinal teas, and the popotillo is highly regarded by some as a tonic for the liver and gall bladder. The candelilla is a good source of wax, and guayule has been used in the manufacture of rubber. Mule and whitetail deer are the principal game animals in Terrell County. Other game species are the javalina (collared peccary), wild turkey, mourning dove, white-winged dove, and blue quail. Furbearers include the grey fox, coyote, raccoon, bobcat, ringtailed cat, and mountain lion. Many varieties of ducks and other birds use Terrell County's stock ponds and pastures as resting and nesting places during their seasonal migrations.
Almost all of the area's agricultural income derives from livestock, especially Angora goats and sheep; mohair and wool are the most important agricultural products. Some cattle are also raised in the area, and some local growers produce pecans. Mineral resources include limestone, salt, natural gas, and petroleum. In 1982 almost 31,016,000 cubic feet of gas-well gas, about 398,000,000 cubic feet of casinghead gas, and 47,330 barrels of crude oil were produced in the county. The county is on the main line of the Southern Pacific Railroad, and U.S. Highway 90 crosses the southern part of the county east to west.
There are many burned-rock mounds, called middens, on the ranches of Terrell County. Numerous rockshelters and caves with smoked walls and ceilings, mute evidence of long habitation by early Indian peoples, also exist in the area. In some of the shelters Indian paintings are to be found. The most extensive pictographs, on the cliff wall above Myers Spring near Dryden, include drawings of a church, deer, a large bird, and people dancing and hunting. Overpainting on these pictographs makes it clear that they were probably painted by several different Indian cultures. Arrowheads found in the area are dated by archeologists as belonging both to prehistoric and historic periods. Bits of reed matting, parts of baskets, pieces of reed sandals, and evidences of burials have also been found in the caves. Many grinding holes in flat rock surfaces, as well as manos (round stones worn smooth by pounding and rubbing), tell of the early Indians' diet of mesquite beans and dried, roasted, and ground sotol.
A number of Spanish explorers probably crossed what is now Terrell County in the sixteenth and seventeenth centuries. In 1729 Capt. José de Berroterán explored the terrain along what is now the southern border of the area. At a spring near the site of present-day Dryden, he is said to have erected a large wooden cross. Six years later another Spaniard, Blas María de la Garza Falcon, found the cross while conducting an expedition in the area and named the spot Santa Cruz de Maya. The future county was crossed in 1848 by the unsuccessful Hays-Highsmith expedition while it was trying to establish a trade route between Chihuahua and New Orleans. In 1851 Lt. Nathaniel Michler, working under Major William H. Emory, mapped this portion of the boundary between Mexico and the United States. The Terrell County area was crossed by caravans of camels in the "camel experiment" conducted by the United States Army in 1859–60.
Between 1871 and 1905 the area was part of Pecos County. The region was opened for settlement in the early 1880s in anticipation of the arrival of the Texas and New Orleans Railroad, which had surveyed a route through the region. Cyrus W. (Charley) Wilson developed a townsite called Strawbridge at a designated stop along the railroad, where he bought the land and laid out streets and lots. In May 1882, when the Galveston, Harrisburg and San Antonio Railroad reached the site, the town was renamed Sanderson after a railroad engineer. Charles Downie, a Scot, the first permanent sheepman in the area, homesteaded there in 1881. He eventually increased his holdings to around 150,000 acres. Dryden, the only town besides Sanderson in the county, was also started in 1882 when the railroad built through the area. It was headquarters for the Pecos Land and Cattle Company, a huge ranching operation in the earliest days of White settlement. Goldseekers traveled to the county, as did a number of outlaws and gunmen. Roy Bean operated a saloon at Sanderson. By 1900 the population of this community was 112, and post offices had been established there and in Dryden.
Terrell County was formed by an act of the Texas legislature on April 8, 1905, and organized on July 27 of that year. Sanderson became the county seat. Cattle and sheep ranching have dominated the county's economy since its beginnings. In 1910 the United States census reported sixty ranches, encompassing 621,000 acres, in the county. More than 111,000 sheep, almost 19,000 goats, and about 20,000 cattle were reported in the county that year, but only 800 acres was classified as "improved." In 1930 the county had 141 ranches, encompassing almost 1,450,000 acres, and more than 351,000 sheep and about 10,000 cattle were reported; only 43 acres of cropland was harvested in the county that year. Terrell County's population rose gradually from 1,430 in 1910 to 2,680 by 1920 and to 2,952 by 1930. The number of ranches in the area dropped slightly during the Great Depression of the 1930s; 136 remained in 1940. The population rose slightly during the depression to reach 2,952 by 1940. A number of stations-Emerson, Gavilan, Feodora, Shaw, Thurston, Watkins, Malvado, Lozier-were built along the Southern Pacific Railroad between 1946 and the 1960s. Each station, or "section," had a foreman and a crew of laborers who were responsible for maintenance and repairs over about ten miles of track. The foreman and the laborers lived with their families in railroad-owned houses at the section. By the 1980s almost all had been eliminated by the railroad company: the buildings were gone, and the remaining laborers had become "floating" crews who traveled up and down U.S. 90 beside the tracks to wherever their services were needed.
The oil and gas industry became increasingly important to Terrell County's economy after 1957, when the Brown-Bassett gas field was discovered in the northeast part of the county. Only gas was produced until the 1970s, when high petroleum prices encouraged limited oil production as well. Sanderson was struck by a flood on June 11, 1965, in which twenty-six people died. Two of them were never found. Heavy rains to the west and northwest of the town, on the watersheds of the Sanderson Canyon draw and the Three-Mile draw sent the floodwaters through the town, destroying many homes and businesses. By the mid-1980s, a flood-control project funded by the federal government was nearing completion, with eight of eleven projected dams completed or under construction.
In the mid-1980s sheep continued to outnumber other domesticated animals in Terrell County. In 1984 county stockmen were raising 90,000 sheep, 72,000 goats, and 9,500 cattle. Sheep and goats are susceptible to such predators as coyotes and mountain lions, however, and in the 1980s a number of local ranchers blamed predators from nearby Big Bend National Park for livestock losses.
The voters of Terrell County supported Democratic candidates in almost every presidential election between 1908 and 1948; the only exceptions occurred in 1924, when Republican Calvin Coolidge carried the county, and in 1928, when Herbert Hoover did. The county's voters were less predictable in elections between 1952 and 1992, however. The county was carried by Republican Dwight D. Eisenhower in the 1952 and 1956 elections; in 1960 Democrat John Kennedy won in Terrell, as did Democrat Lyndon B. Johnson in 1964. Republican Richard Nixon took the county in the presidential elections of 1968 and 1972, but Democrat Jimmy Carter won there in 1976. Republican Ronald Reagan carried Terrell in 1980 and 1984, but Democrat Michael Dukakis won there in 1988, and William J. Clinton took the county in 1992.
The county population rose to 3,189 by 1950 but then continued to drop, falling to 2,600 in 1960, 1,940 in 1970, and an estimated 1,500 in 1982. The movement to the cities for jobs, the elimination of many jobs by the railroad company, and an increase in absentee ownership of land all contributed to the decline. By 1990 only 1,410 people were living in the county. As of 2014, 927 people lived in the county. About 45.8 percent were Anglo, 1.2 percent African American, and 47.8 percent Hispanic. In the mid-1980s Dryden was still an important community in the county, having a post office, service stations, and a general store. It also served as a rallying point for "float trippers" at the end of their runs down the lower canyons of the Rio Grande. The river runners often end their journeys on a ranch south of Dryden. In 2014 there were thirteen residents in Dryden. Sanderson (population, 806) is the county's commercial center. The town, sometimes called the "Gateway to Big Bend," hosts a rodeo in April or May, a Street Dance in July, and the County Fair in January.