Lamb County is on the southern edge of the Panhandle, in the South Plains portion of the state, bordered on the east by Hale County, on the south by Hockley County, on the west by Bailey County, and on the north by Castro and Parmer counties. The center of the county is located at 34°02' north latitude and 102°20' west longitude. The entire county is atop the high plains. Littlefield, the county seat, is in the southern part of the county on U.S. Highway 84, forty miles northwest of Lubbock. The county was named for George A. Lamb. It occupies 1,022 square miles of level plains dotted with playas and a few low hills. Soils range from sandy to brown and support a variety of agricultural crops, including grain sorghum, cotton, corn, wheat, and soybeans. A relatively small amount of oil production occurs in the southern part of the county. The major physical features of the county are the dry bed of the North Fork of the Double Mountain Fork of the Brazos River, also known as Blackwater Draw, and a range of low-lying sand hills roughly following the course of Blackwater Draw as it meanders southeast across the northern section of the county. Two other tributaries of the Brazos, Running Water Creek and Yellow House River, also traverse the county. Four small lakes are found in the western half of the county: Soda Lake in the northwest and Bull Lake, Illusion Lake, and Yellow Lake in the southwest. Elevations in Lamb County range from 3,400 to 3,800 feet above sea level. Annual precipitation averages 18.04 inches per year, and the growing season lasts 194 days. Temperatures range between an average minimum temperature of 24° F in January and an average maximum of 93° in July.
The South Plains of Texas was long the domain of Apachean peoples until they were pushed out of the region by the more warlike Comanches around 1700. The Comanches ruled the Panhandle-Plains until the Red River War of 1873–74, when they were crushed by the United States Army. In 1875 the Comanches left the Panhandle-Plains for reservations in Indian Territory, leaving the region to the buffalo hunters. Between 1876 and 1880 the huge buffalo herds on the Texas Plains were almost exterminated, leaving the area open for occupation by cattlemen. Lamb County was established by the Texas legislature in 1876 from lands previously assigned to Bexar County.
Ranching arrived in the area when the huge XIT Ranch, occupying 3,050,000 acres of land, was established in 1885. Most of the eastern and northern part of the county was XIT land. C. C. Slaughter's Running Water Ranch occupied land in Lamb, Hale, Swisher, and Castro counties. The county's economy developed slowly as large-scale ranching completely dominated the area during the late nineteenth century and into the first years of the twentieth. Only four people lived in the county in 1890, and as late as 1900 there were only thirty-one people there. That year five ranches, encompassing 529,000 acres, had been established, and 10,908 cattle were reported. No crops were reported in the agricultural census taken in 1899. In the early 1900s the large ranches began to break up, and farmers began to establish themselves. In 1901 the XIT decided to sell its holdings. George W. Littlefield purchased most of the Yellowhouse Division of the XIT, 300,000 acres, and established the LFD Ranch in 1901. The Halsell family, led by William E. Halsell, purchased 185,000 acres of the old XIT Ranch's Springlake and Yellowhouse divisions to be operated as the Mashed O Ranch. These two new ranches joined an older ranch that occupied parts of Hockley, Lubbock, Lamb, and Hale counties. In 1908 Slaughter sold much of his Running Water Ranch to land speculator William P. Soash. These lands lay around the tiny community of Olton. Soash sold the land to incoming farmers and stock farmers, and on June 20, 1908, Lamb County was organized with Olton as the seat of government. By 1910 there were ninety-two ranches and farms, and the population had risen to 540. The county was primarily a ranching area with a small number of merchants, farmers, and stockfarmers; in 1910, 40,355 cattle were reported in the county, while only 489 acres were planted in corn, the county's most important crop that year.
Immigration into the area was encouraged in the early 1910s when the Santa Fe Railroad made plans to build a branch line from Lubbock to Clovis, New Mexico, bisecting Lamb County from southeast to northwest and crossing George Littlefield's LFD Ranch. Littlefield cooperated with the railroad in bringing the line to fruition and helped to establish a townsite, ultimately known as Littlefield, on the railroad. Preliminary work on the Lubbock-Clovis line began as early as 1909, and by 1912 the townsite of Littlefield had been laid out. George Littlefield initiated land sales of major ranches in 1912 when he began to sell off parts of the LFD Ranch. Once the railroad was finished in March 1913 and the town of Littlefield established, farmers began to move into the area in larger numbers. By 1920 the county had 172 farms and ranches, and the population had increased to 1,175. Cropland expanded while the number of cattle declined. About 28,000 cattle were counted that year, and 8,517 acres were planted in sorghum, 2,551 acres in wheat, and 400 acres in cotton. During the 1920s the old ranchers realized great profits from land sales to thousands of newly arriving farmers; all three of the county's large ranches began to market their acreages. Littlefield accelerated his sales in the 1920s, the Halsells initiated land sales in 1923, and the Ellwoods began to sell out in 1925. As land sales progressed, small farming communities cropped up: Sudan was established in 1917 and was followed by Pep (1923), Amherst (1923), Earth (1924), Witharral (1924), Spade (1924), and Rocky Ford (1926). The number of farms increased to 632 by 1925 and to 2,381 by 1930. Most of the new farmers came to grow cotton, which during the 1920s moved from a relatively minor crop to the center of the area's economy. By 1930 cotton occupied 100,700 acres in Lamb County. Many local farmers also began to raise poultry during the 1920s; by 1930, 135,000 chickens were reported on farms, and farmers sold 487,000 dozens of eggs. The population grew during the 1920s, and by 1930 the census listed 17,452 residents. The county's emerging agricultural economy held through the Great Depression. Though the number of farms decreased slightly (to 2,167), cropland harvested increased from 316,214 in 1930 to 350,344 in 1940; cotton land increased to 119,000 acres. The population also grew slightly during the 1930s to reach 17,606 by 1940.
The county's rapid economic development also shaped its political geography. In the years after 1920 Littlefield developed into the county's leading community, and by 1930 it had about three times the population of Olton. After three attempts to change the county seat from Olton to Littlefield (in 1929, 1932, and 1937), Littlefield residents finally succeeded in 1946. As Lamb County evolved in the years after World War I a transportation system slowly emerged. A major route, State Highway 7 (now U.S. Highway 84), from Lubbock to Farwell and Clovis, was fully operational by the mid-1920s. A dirt road linked Littlefield to Hale Center, and another dirt lane ran westward from Littlefield to the county line. During the 1930s and 1940s the county built a network of farm-to-market roads, which were paved in the 1950s and 1960s. After World War II Littlefield developed into a trade center; meanwhile, oil discoveries in the very southern part of the county in 1945 also boosted Littlefield's economy. This production, although relatively small, was a welcome addition to the local economy. Over 326,000 barrels of oil were produced in the county in 1948; 419,000 barrels in 1956; 721,000 barrels in 1974; 1,096,000 barrels in 1978; and 1,103,000 in 1982. In 1990 519,000 barrels were produced. The population of the county increased after World War II to reach 20,015 in 1950 and 21,896 in 1960. Mechanization of agriculture and consolidation of farming operations pushed the population down somewhat in the 1960s, but it grew again during the 1970s, partly because of expanding oil operations in the area. The number of residents was 17,770 in 1970, 18,669 in 1980, and 15,072 in 1990. As of 2014, the population was 13,574. Of those, 40.6 percent were Anglo, 5.1 percent African American, and 53.8 percent Hispanic. By the 1980s U.S. Highway 70, from Plainview to Muleshoe, had been built across the northern part of the county, U.S. 84 angled across the southwestern half, and a network of farm-to-market roads linked the county's many rural communities to Littlefield and to both U.S. 70 and U.S. 84.
In national elections the voters of Lamb County supported Democratic candidates in almost every presidential election held between 1908 and 1964; the only exceptions occurred in 1928, when a majority supported Republican Herbert Hoover, and in 1952, when they supported Dwight D. Eisenhower. In presidential elections between 1964 and 1992, however, the county consistently voted Republican, except for 1976, when the voters supported Jimmy Carter. In the 1980s Lamb County had a diversified economy based on agriculture but enhanced by commercial, industrial, and petroleum production. The county averaged $130 million a year in agricultural production with half coming from cotton, corn, wheat, grain sorghum, and soybean farming and the other half from cattle, hog, and sheep feedlot operations. By 1980, 447,000 acres (70 percent) were under cultivation for farm crops. About 210,000 acres were irrigated. Littlefield had agribusinesses, retail facilities, a textile mill, a fertilizer plant, and an irrigation-systems factory, as well as a hospital and nursing homes. Oil production averaged $3.5 million a year, while manufacturing added another $9.2 million a year. The county's primary towns were Littlefield (population, 6,238), Olton (2,124), Earth (1,023), Sudan (935), Amherst (697), and Springlake (106). Other communities included Spade, Fieldton, Circle, and Cofferville.