Dawson County lies on the eastern edge of the Llano Estacado on the southern High Plains. The center point of the county is at 32°45' north latitude and 101°57' west longitude, sixty miles south of Lubbock. The county comprises 902 square miles of rolling prairie, broken on the east. The land, surfaced with sandy and loam soils, drains to playas. The altitude ranges from 2,600 to 3,200 feet above mean sea level. The average annual rainfall is 16.09 inches. The average minimum temperature in January is 28° F; the maximum average in July is 94°. The growing season averages 212 days. The county is crossed by Sulphur Springs Draw, a natural trail used by the Indians since prehistoric times and by the first White men who entered the South Plains. The area was the summer home of Comanches and Kiowas, who moved from waterhole to waterhole in a region that White men supposed waterless. A portion of the future county was included in a Mexican grant issued to Dr. John Cameron on May 21, 1827. Cameron contracted to settle 100 families, but there is no record of any attempt to carry out the contract.
In the fall of 1875 the Twenty-fourth United States Infantry, commanded by Col. William Rufus Shafter, visited the area to prepare a report on the local Indians. On October 18, 1875, the company discovered an Indian encampment at Laguna Sabinas or Cedar Lake, the legendary birthplace of Quanah Parker; the band, however, escaped to the west. The Shafter party made the first wagon roads on the plains and reported favorably on grazing conditions, but the Indian menace remained too severe for immediate settlement. The Nolan expedition of 1877 got lost in the area of the future Dawson and Lynn counties, and several members of the party of sixty died of thirst. Buffalo hunters, more than soldiers, were probably responsible for driving the Indians from the area. A surveying party for Texas and Pacific Railway lands in 1875 reported the presence of thousands of buffalo, and hunters moved in. As cattlemen learned that the grass on the Plains would produce fat cattle, ranchmen moved from the Lower Plains south of the Caprock to the new lands. By the mid-1880s four ranches, C. C. Slaughter's Lazy S, the TJF, the Fish, and the Bartow, occupied most of the land in Dawson County. The Texas and Pacific reached Big Spring in neighboring Howard County in 1881, and that community served as the shipping point for the area. By 1890 there were 28,536 cattle reported in the county.
The first decade of the twentieth century was a time of dramatic growth for Dawson County, as the population jumped from thirty-seven people in 1900 to 2,320 in 1910, and the number of ranches and farms increased from four to 330. Between 1902 and 1905, as the grazing leases expired, Dawson County lands were filed on for settlement. Prospective settlers waited in line in Big Spring for as long as six weeks when choice pieces of land were released. In 1907 the first railroad land was sold at from three to five dollars an acre. One large ranch was not opened for settlers until 1946, when it sold for sixty-five dollars an acre. The first school in Dawson County began in one room of the Mullins ranchhouse in 1902. The first church was organized by the Baptists in Chicago in 1904, but the Methodists built the first church building in Lamesa in 1907; it was used alternately by four communions on successive Sundays. The first post office was north of Lamesa at the Bartow ranch headquarters, where residents produced a wagonload of mail to prove to postal authorities that a post office was needed. They were so impressed by the amount of their own handiwork that they humorously named their post office Chicago. That same year, the Dawson County News was begun by J. E. Garrison and the Dawson County Bank was organized. Dawson County, named for Nicholas Mosby Dawson, had been formed on August 21, 1876, but was attached to Howard County for judicial purposes until February 13, 1905, when separate organization was authorized. Dawson County's first election to choose officials and select the county seat was held on March 20, 1905. The contesting towns, Lamesa and Chicago, were only two miles apart. Lamesa won by five votes, but a movement was already afoot to consolidate the towns and all businesses and residences in Chicago were moved into Lamesa. After six years of effort to secure a railroad, the Santa Fe was built into Lamesa in 1911.
Although the first bale of cotton produced in the county was grown in 1903, cotton did not become a main crop until 1914 or 1915. During World War I prices were good for the bumper crops produced. Settlers poured in, bought pieces of the newly partitioned ranches, and sent land prices soaring. More than 24,000 acres was planted in cotton by 1920; in 1930, 182,527 acres, well more than 60 percent of all county cropland harvested, was devoted to cotton production. The county population grew to 4,309 by 1920 and increased almost threefold during the 1920s to reach 13,373 in 1930. However, by 1930, under the impact of adverse farming conditions and prices, almost 70 percent of the county's 2,218 farms were worked by tenants. The Great Depression caused many businesses to fail, but other industries that developed in the county during the 1930s partially offset these losses. The dairy industry prospered. A powdered-milk plant built in 1929 was closed by the depression but began seasonal operation in 1932 making powdered eggs. Oil development began in 1934. Twenty-eight wells were producing in the Welch community and two in the southeastern part of the county in 1946. Intermittent wildcatting has continued. In 1940 the county had a population of 15,367. Agriculture was more diversified, as county farmers grew sorghum on twice as much land as was planted with cotton. During World War II Dawson County provided more men per capita for the armed services than did any other county in Texas. Despite critical farm-labor shortages, an organization of merchants, farmers, and the chamber of commerce met every agricultural quota set for the county. The egg-drying plant turned its entire facilities over to lend-lease production. Dawson County was one of the five counties in the state to win the coveted Army-Navy "E" award. Lamesa Field, an army airfield, was established in 1942 and deactivated two years later.
Irrigation was introduced into the county in the late 1940s, and cotton once again dominated the agricultural economy, with some 300,000 acres planted in 1950 and more than 180,000 in 1960. The county population reached 19,113 in 1950 and an all-time high of 19,185 in 1960, but declined thereafter to 16,604 in 1970 and 16,184 in 1980. New agricultural methods and the increasing use of farming technology saw the number of farms in the county shrink from a peak of more than 2,000 in 1930 to 841 in 1960 and 581 in 1980. The population of the county was predominantly White through the 1930s. In 1930 there were only 261 African Americans in the county, or some 2 percent of the population. The number of Blacks increased to 537 in 1950 and 873, or 5 percent of the county population, in 1970. Thereafter the number of Black residents began to decline. The Hispanic population of Dawson County began to increase dramatically in the mid-twentieth century. Almost 40 percent of the population was Hispanic in 1980 and more than 42 percent in 1990. Politically, the county held to the Democratic party in national elections through 1964, with the exceptions of 1928, 1952, and 1960. From 1968 through 1992 Dawson County voters consistently supported Republican presidential candidates.
The mainstays of the county economy in the 1980s were agribusiness and oil. Dawson County was second in the state in cotton production in 1980, and through the 1980s cotton continued to be the most important agricultural product. Sorghum and wheat were also important crops, and cattle and hogs were raised. Between the first discovery of oil and 1990, oil production totaled 294,809,170 barrels. In 2014 the county population was 13,372. County towns included Lamesa (9,383), Ackerly (232 in Dawson County), O'Donnell (792 in Dawson County) and Los Ybanez (20).