Until the frontier reached the Hartley County region in the 1870s, the area was just a small part of the huge, vacant High Plains, which stretch from Texas to Canada. An Apachean culture occupied the Panhandle-Plains area in prehistoric times; the modern Apaches emerged then but were pushed out of the region about 1700 by the Comanches, who ruled the area until they were defeated in the Red River War of 1873–74 and subsequently removed to Indian Territory. In 1876 the Texas legislature marked off Hartley County from land formerly assigned to Bexar and Young counties. Due to its proximity to both the Canadian River and New Mexico, Hartley County undoubtedly witnessed the comings and goings of Comancheros, ciboleros, and pastoresqqv as they ventured eastward from New Mexico into Comanchería on the Great Plains. The pastores, in fact, continued to migrate yearly after the Indian era and made up a large part of the regional population and economy into the early 1880s.
With the Indians removed, cowmen entered the region, and in the late 1870s and 1880s Hartley County changed from raw frontier into the domain of the established rancher. The county quickly became a part of the huge ranching industry that developed in Northwest Texas after the Civil War. Between 1876 and the 1890s many well-known Panhandle ranches blossomed on Hartley County soil. The famous XIT Ranch was formed along the western border of the Panhandle in 1882 and occupied the western third and the southern third of Hartley County. Other ranches (including the LE Ranch, the LIT Ranch of George W. Littlefield, and the Matador Ranch of the Matador Land and Cattle Companyqqv) purchased Hartley County lands between 1882 and 1902.
In 1880 the county had only 100 residents; by 1890, 252 people lived in the area. According to the United States agricultural census, forty-eight ranches and farms, encompassing almost 180,000 acres, had been established in the county by 1890, and the economy centered on cattle and sheep ranching. More than 11,100 cattle and 3,200 sheep were counted in the area that year, while crop farming had only begun to be established in the county. Only 161 acres was planted with corn, and 8 acres with wheat; another 102 acres was planted in cotton.
In 1891 the county was organized with the tiny town of Hartley as county seat. County judge Rucker Tanner presided over a commissioners' court made up of Dick Pincham, W. C. Ferguson, George W. Knighton, and G. W. Lambert. Ben Lawson became the county clerk, and J. M. Robinson was made sheriff. M. Montoya became the tax assessor-collector, and J. H. Little was named county attorney. After an election in 1896, the county government was moved to Channing, where it remained despite periodic attempts to move it again; in 1903 a final election confirmed Channing as the county seat. In 1898 a weekly newspaper, the Channing Courier, was started.
By 1900 cattle ranching in the county had expanded considerably, though the number of ranches had declined. Almost 143,500 cattle were reported on the twenty-seven ranches and farms counted by the census, though this figure was probably inflated by Hartley County ranchers reporting their grazing property in other counties. No sheep were reported, and sorghum was the only crop of consequence grown in the county at that time. The county had 377 residents that year.
Railroads first entered Hartley County in 1888, when the Fort Worth and Denver Railway extended its main line westward from Amarillo through the sites of Channing, Hartley, and Dalhart, to Texline, in Dallam County. The Chicago, Rock Island and Mexico Railway, building southwesterly from Enid, Oklahoma, to Tucumcari, New Mexico, entered the county through Dalhart in 1901. Thus, with two rail connections to the outside world, Hartley County ranches shipped their cattle more easily than before, and settlers began to arrive in larger numbers. Successful cereal-crop experiments conducted by the United States Department of Agriculture in Channing, Dalhart, and Amarillo between 1903 and 1913 also helped to hasten the movement of farmers into the area.
Between 1900 and 1930 the number of farms and ranches in Hartley County grew significantly, and farming began to play a larger role in the local economy. The number of farms and ranches in the county rose to 165 by 1910, then dipped to 139 in 1920 before rising again to 218 by 1925 and to 264 by 1930. Crop production particularly increased during the 1920s; the number of acres devoted to corn, for example, rose from 244 in 1920 to 9,500 in 1930, while the number of acres planted in wheat rose from 796 to 9,285. Poultry production also became more important to the local economy during this period; by 1930 almost 16,000 chickens were reported in the county, and that year Hartley County farmers sold almost 45,000 dozen eggs. Nevertheless, cattle ranching remained at the center of the local economy; more than 32,300 cattle were counted on local ranches in 1910, almost 43,000 in 1920, and about 34,700 in 1930.
During the first half of the twentieth century, a road system was built in the area. By 1927 much of what later became U.S. Highway 87, running from Amarillo to Dalhart, had been built across the northeastern corner of the county, but it remained unpaved until the end of the 1930s. By the end of the next decade U.S. Highway 54, crossing the western part of the state, was paved, and a paved road, State Highway 51 (now U.S. 385), also connected Hartley and Channing.
The grim days of the Dust Bowl and Great Depressionqqv set the area back during the 1930s. More than 20 per cent of local farmers were compelled to give up their lands, and by 1940 only 207 farms remained in the county. As a result, the population dropped to 1,873 by 1940. The establishment of Dalhart Army Air Field in northern Hartley County during World War II helped to revive the economy, however, and crop production also picked up as farmers increasingly tapped the huge Ogallala Aquifer for water; during this time Hartley County developed an economy based on both ranching and wheat, corn, and sorghum culture.qqv Irrigation of farmland steadily increased during the postwar years, and by 1980 more than 100,000 acres of local cropland was irrigated. That year the county earned $95 million in agricultural receipts, with ranching accounting for about $72 million and farming more than $22 million. In 2002 the county had 253 farms and ranches covering 789,289 acres, 64 percent of which were devoted to pasture and 35 percent to cropland. In that year farmers and ranchers in the area earned $447,275,000 (up 27 percent from 1997); livestock sales accounted for $378,899,000 of the total. Cattle, corn (including blue corn and popcorn), wheat, sorghum, and hay were the chief agricultural products. Natural gas production totaled nearly 6.6 billion cubic feet in 1982. In 2000 more than 2.6 billion cubic feet of gas and about 392,000 barrels of oil were produced in Hartley County; by the end of that year 6,183,825 barrels of oil had been taken from the area since 1937. The population of Hartley County steadily increased from the 1940s to the 1980s, rising to 1,913 in 1950, 2,171 in 1960, 2,782 in 1970, and 3,987 in 1980. It dropped during the 1980s, however, and in 1990 stood at 3,634; in 2000 there were 5,537 people living there. Incorporated communities in the county include Channing, the county seat (2000 population, 356), and Dalhart (7,237, most of whom live in Dallam County). Other communities include Hartley (441), Middle Water, and Romero. The county hosts the Matador Cowboy Reunion, held in Channing each August, and the XIT Rodeo and Reunion, held in Dalhart in July and August. From the beginnings to 1948 the county voted solidly Democratic in presidential elections, with the exception of its support of Herbert Hoover in 1928. From 1952 to 2004, however, county voters chose Republican candidates in every presidential election except those of 1956 and 1964.