Roberts County is in the northeastern Panhandle, bounded on the north by Ochiltree County, on the east by Hemphill County, on the south by Gray County, and on the west by Hutchinson County. The center of the county lies at 35° 30' north latitude and 100° 32' west longitude. The county was named for two distinguished Texans with the surname Roberts, John S. Roberts and Oran Milo Roberts. Miami is the county seat. The county is crossed by U.S. Highway 60, State Highway 70, and the Atchison, Topeka and Santa Fe Railway. Roberts County covers 924 square miles of rolling plains with elevations that range from 2,467 to 3,219 feet above sea level. Annual rainfall is 20.7 inches. January's average minimum temperature is 19° F; July's average maximum is 94° F. The county has a growing season of 192 days, the soils are black, sandy loam with clayey subsoils, and between 11 and 20 percent of the land is considered prime farmland. The county is in the Rolling Plains vegetation area, with tall grasses and mesquite and live oak trees and is drained by the Canadian River and its numerous tributaries.
Prehistoric cultures occupied this region, followed by Plains Apaches. In the early eighteenth century the Apaches were pushed out by the Comanches, who then dominated the area of the Texas Panhandle until the 1870s. The nomadic Comanches hunted the immense herds of buffalo that ranged through the area that would become Roberts County. The actions of Ranald S. Mackenzie and federal troops in the Red River War of 1874–75 removed the Indian threat. At the same time buffalo hunters killed off the great herds of bison. In 1876 Roberts County was carved from Bexar County and the Clay Land District and attached to Wheeler County for judicial purposes. The first settler was Bill Anderson, who arrived the same year. Henry Whiteside Cresswell established the first ranch on Home Ranch Creek in 1877. Cresswell included most of Roberts County in his Cresswell Ranch and ran 45,000 cattle on land spanning several counties. Marion Armstrong opened a stagecoach stand on Red Deer Creek at the site of future Miami in 1879. There were only thirty-two people in the county in 1880, all of them working on cattle ranches. In 1885 Cresswell moved his ranch headquarters north to Ochiltree County.
In 1887 the Southern Kansas Railway built a line from the Oklahoma border into the Panhandle, passing through Roberts County and linking up with Panhandle City the following year. Settlers followed in the wake of the railroad, and the town of Miami was platted out along the railroad in the southeastern part of the county in the summer of 1887. Settlers around Miami petitioned for county government, while cattlemen and settlers along the Canadian River in the northern part of the county framed a counter petition with Parnell, a small settlement in the northwestern part of the county, as proposed county seat. The county was organized in January of 1889, and Miami was chosen as the county seat, but the election was declared fraudulent in December, and Parnell was chosen county seat instead. Parnell remained the county seat until 1898, after another election relocated the seat of county government back to Miami. By 1890 Roberts County had a population of 326 and thirty-four farms and ranches. Among the important ranches were the Cresswell Ranch, the Turkey Track Ranch, and the Cross Bar Ranch. Miami prospered as the shipping point for cattle. The county population slowly grew to 620 in 1900, 950 in 1910, and a peak of 1,469 in 1920. The county economy centered on cattle raising, and the number of cattle increased from 30,259 in 1900 to a peak of 48,959 in 1930. During the same period the county developed a modest farming economy, increasing from 3,576 improved acres in 1900 to 44,751 in 1930. Wheat was by far the most important crop, increasing from 1,423 acres in 1910 to 29,350 acres in 1920, to a peak of 34,102 acres, over three quarters of the cropland harvested that year, in 1930. Corn, oats, and cotton were also grown at different times. The Dust Bowl and the Great Depression dealt hard blows to the farming industry of Roberts County, as the number of acres in cultivation declined by a quarter during the 1930s, and the value of county farms dropped by a third. Roberts County's population was relatively static in the 1920s, with 1,457 inhabitants in 1930. Thereafter a long term decline set in, as the county population fell to 1,289 in 1940, 1,031 in 1950, and 967 in 1970 and then recovered slightly to 1,025 in 1990; there were 887 people living in the county in 2000 and 929 in 2010. Throughout its history Roberts County has remained one of the most sparsely populated counties in the state. Most of the inhabitants of the county have been White of English, Irish, and German descent; in 2000 Blacks comprised 0.34 percent of the county's residents and Hispanics made up less than 4 percent of the population.
Agribusiness and oilfield operations came to dominate the county's economy. Oil was discovered in Roberts County in 1945, and 40,126,321 barrels had been produced through 1990. Almost 412,600 barrels of oil and 23,574,562 cubic feet of gas-well gas were produced in the county in 2000; by the end of that year 44,937,568 barrels of oil had been taken from county lands since 1945. Though the number of acres devoted to wheat production never returned to its 1930 level, wheat remained the dominant crop through the 1990s, while the number of cattle raised in the county remained in excess of 30,000 over the same period. In 1982, 98 percent of the land was in farms and ranches, with 9 percent under cultivation. In 2002 the county had 94 farms and ranches covering 494,588 acres, 89 percent of which were devoted to pasture and 10 percent to crops. In that year farmers and ranchers in the area earned $13,232,000; livestock sales accounted for $11,006,000 of the total. Beef cattle were the area's most important agricultural product, but crops such as corn, wheat, sorghum, and soybeans were also grown in the area.
Roberts County voters supported Democratic presidential candidates in all elections from 1892 through 1948, with the exception of Al Smith in 1928. They voted Republican in every presidential election from 1952 through 2004. Religious life in the county in the early years revolved around the Presbyterian, Baptist, and Methodist churches of Miami, all founded in the late 1890s. These denominations were joined by the Church of Christ in 1912 and the Christian Church in 1923. The early settlers of the county also made education a priority, and by 1899 Roberts County had four schools serving 165 pupils. Educational levels have improved dramatically in the county in the second half of the twentieth century. While only 22 percent of the county population had completed high school in 1950, 78 percent were high school graduates in 1980. By 2000, 90 percent had completed high school and more than 25 percent had college degrees. Miami, the county seat and the only incorporated community in the county, had 675 inhabitants in 1990; in 2014 there were 584 people, almost two-thirds of the county's 928 residents, lived there. As of 2014, about 82.9 percent of residents were Anglo, 0.7 percent African American, and 13.4 percent Hispanic. The annual National Cow Calling Contest has been held in Miami since 1949, and there are a number of scenic drives in the county.