Moore County is located in the north central part of the Panhandle of Texas, bordered by Sherman, Hutchinson, Potter, and Hartley counties. Dumas, the county seat, is located in the center of the county, at 101°55' west longitude and 35°50' north latitude, about forty-eight miles north of Amarillo. The area is named for Commodore Edwin Ward Moore, the commander of the Texas Navy during the Republic of Texas. Moore County occupies 909 square miles of the High Plains. The sandy and loam soils support abundant native grasses as well as various local crops such as wheat, corn, milo, and other grains. In general the terrain consists of nearly level prairies varied by the Canadian River brakes in the southeast and by Grapevine, Plum, South Palo Duro, North Palo Duro, and Big Blue creeks, which flow west to east and drain into the Canadian River. Part of Lake Meredith, a man-made lake on the Canadian River, is in the far southeastern corner of the county. Elevations in the county range from 2,900 to 3,700 feet above sea level. Average rainfall is 18.33 inches per year. The average minimum temperature is 20° F in January, and the average maximum is 93° in July. The growing season averages 185 days per year.
Although early Spanish explorers and later American expeditions crossed the county by way of the Canadian River, the entire region remained the domain of Indians from prehistoric times until the 1870s. Following the Red River War of 1874, the Comanches and Kiowas were permanently removed to Indian Territory. In 1876 the Texas legislature formed Moore County from lands formerly assigned to Bexar County, and soon ranchers began moving into the area. Ranching dominated the local economy from the 1870s to the 1920s, when farming began to develop significantly. During 1877 George W. Littlefield established his famous LIT Ranch in southwestern Moore and eastern Hartley counties. Soon others followed. The LX Ranch, with headquarters in Potter County, had substantial Moore County acreage, as did the LS Ranch, which was headquartered in eastern Oldham County. Lesser stock-raising operations developed in the unclaimed ranges between these larger ranches. During the 1880s the local ranching economy stabilized, and the few stock raisers and farmers who lived in the county saw the need for a local government. The founding of the town of Dumas by Louis Dumas and the Panhandle Townsite Company in 1890 encouraged county organization. As a result, Moore County was organized with Dumas as the county seat following an election held on July 5, 1892. By 1900 there were fifty-seven ranches and farms in the county, encompassing about 115,500 acres, and the United States agricultural census reported 6,885 cattle and 300 sheep. Only 1,708 acres were classified as "improved," and only forty-two were devoted to corn, at that time the county's most important crop. The county population grew from 15 to 209 between 1890 and 1900.
As early as the 1890s local stock raisers and a few farmers began to plant small amounts of corn, wheat, and grain sorghums. Farming continued on a limited scale until the years during and just after World War I, when worldwide demand led to a boom in farming. Thousands of acres of Moore County land were first cultivated between 1910 and 1920, as many of the old ranches began to sell their lands to newly arriving farmers. By 1920 there were ninety-three farms and ranches in the county; more than 11,000 acres were planted in sorghum, and another 2,733 acres were devoted to wheat. According to the U.S. census, there were 571 people living in the area at that time. As grain prices fell during the 1920s, cotton was introduced as a supplementary crop. By the end of the 1920s the local economy was based on a mix of cattle ranching and wheat and grain farming. In 1930 more than 24,600 acres were planted in wheat, and over 8,000 in barley. By that year 174 farms and ranches had been established, and the area's population had increased to 1,555. The agricultural economy continued to expand even during the Great Depression of the 1930s. By 1940 more than 62,400 acres were devoted to wheat production; overall, the number of acres of cropland harvested in Moore County rose from about 49,000 in 1930 to almost 90,600 by 1940.
In the mid-1920s discovery of the Panhandle field changed the complexion of Moore County entirely (see OIL AND GAS INDUSTRY). Gas reserves were located in Moore County as early as 1921, and large-scale commercial oil and gas production began in 1927. The Apache Refining Company built a plant north of Dumas at a site which became Sunray. Between 1927 and 1932 Skelly, Phillips, and Shamrock all built refineries. In 1938 almost 469,000 barrels of crude oil were produced in the county. Due in large part to the new petroleum industry, the population grew significantly, rising to 4,461 by 1940. The town of Cactus came into existence during World War II, when the United States government constructed a nitrogen-producing plant near Etter. This plant brought a large influx of people into surrounding towns such as Dumas and Sunray. The discovery and exploitation of oil and gas greatly influenced Moore County. Railroads, which had long ignored the area, quickly appeared. In 1930 the Chicago, Rock Island and Pacific built a spur line from Dalhart to Morse, which crossed the northern part of Moore County through Etter and Sunray. The North Texas and Santa Fe Railway built through the county in 1931 as it extended a line from Spearman to Amarillo through Etter and Dumas. A highway system to serve the oil, gas, and refining industry also developed. In the 1920s only one main route, U.S. Highway 287 (originally 385), crossed the county as it ran from Amarillo to Dumas, then became a smaller road as it went on from Dumas to Stratford. In the following decades a network of paved farm, ranch, and oilfield roads developed to link the county to the main north-south road, U.S. Highway 87, which runs from Amarillo to Dalhart through Dumas and Hartley. Since the 1930s the production of oil and, more importantly, of natural gas has dominated the local economy. Refining, generation of electricity, and even smelting operations developed during the 1930s and 1940s to take advantage of cheap and abundant fuels. Likewise, large pipeline systems originate in the county and carry gas products throughout the region. The growth and coexistence of ranching, farming, and the oil and gas industry resulted in an extensive economic system and attracted a substantial number of newcomers. The county's population increased to 13,349 by 1950 and to 14,773 by 1960 and then continued to rise, to 16,575 by 1980, to 17,865 by 1990, to 20,121 by 2000, and to 22,148 in 2014. Of those, 35.9 percent were Anglo, 2.7 percent African American, and 52.9 percent Hispanic.
In presidential elections the voters of Moore County supported Democratic candidates between 1892 and 1952 but generally voted Republican between 1956 and 2004. The only exceptions occurred in 1964, when most voters supported Lyndon B. Johnson, and in 1976, when they supported Jimmy Carter. In 1980 the local agricultural economy produced roughly $96 million worth of products, with livestock accounting for about 75 percent of the total. In the early 1950s irrigation was brought into Moore County. The first irrigation wells were drilled near Sunray, and by 1983 there were about 1,200 such wells irrigating roughly 205,000 acres of wheat, corn, and other grain crops. In 2002 the county had 276 farms and ranches covering 549,000 acres, 49 percent of which were devoted to pasture and 50 percent to crops. In that year farmers and ranchers in the area earned $303,273,000; livestock sales accounted for $260,839,000 of the total. Fed beef, corn, wheat, grain sorghum, and stocker cattle were the chief agricultural products. Oil, gas, and petrochemical production amounted to around $160 million during the 1980s. Oil production totaled almost 795,000 barrels in 1990; in 2000 almost 325,000 barrels of oil and about 5.5 billion cubic feet of natural gas were produced in the county. By the end of that year 28,830,253 barrels of oil had been taken from Moore County lands since 1936. Communities in the county include Dumas (population, 14,926), the county seat; Cactus (3,169); and Sunray (1,916). Dumas is the home of the Moore County Historical Museum and hosts Dogie Days in June and the county fair in September.