Garza County is in Northwest Texas, partly on the Llano Estacado and partly in the breaks of the lower plains. It is bordered on the north by Crosby County, on the west by Lynn County, on the east by Kent County, and on the south by Borden and Scurry counties. Its center point is 33°10' north latitude and 101°20' west longitude, forty-two miles southeast of Lubbock. The county was named for a pioneer Bexar County family of which José Antonio de la Garza was a well-known member. It covers 914 square miles of rough, broken land drained by tributaries of the Brazos River; elevations vary from 2,100 to 3,000 feet above sea level. The area's sandy, loamy, and clay soils support grass, small mesquite, and thorny scrubs and cacti. The county averages 18.91 inches of rainfall per year and has an average minimum temperature in January of 28° F and an average maximum in July of 95°. The growing season averages 216 days.
Evidences of early man found in Garza County include Clovis spearheads; in 1934 archeologists also discovered the sixteen-foot-long tusk of a prehistoric imperial mammoth. A type of arrowpoint used by hunters before A.D. 1500 was uncovered in the county during the 1960s and named the Garza point. From about 1700 to the 1870s the region was dominated by Kiowas and by Comanches of the Wanderers band, who hunted in the area. These Indians held the Southern Plains for 175 years before yielding to the United States Army in the 1870s.
Garza County was formed from Bexar County in 1876. It began to be settled by ranchmen during the mid-1870s, when buffalo hunting had nearly devastated the herds. Two of the earliest ranchers in the county were Andy and Frank Long, who stocked the range south of the Double Mountain Fork of the Brazos for their OS Ranch. In 1879 W. C. Young and Ben Galbraith established the Llano Cattle Co in the northwest part of Garza County. The ubiquitous West Texas rancher John B. Slaughter used Garza County rangeland during the 1870s. In 1880 the census counted thirty-six residents in the county. The last Indian raid in the county occurred in 1883 at the Curry Comb Ranch, owned by the Llano Cattle Company; in 1884, the Square and Compass Ranch put up the first barbed wire fence in the county. The disastrous winter of 1885–86 (see BIG DIE-UP) and the drought of 1886 discouraged some of the early ranchers, and by 1890 only fourteen residents remained. During the 1890s, however, other ranchers and a few farmers began to move in and drilled wells to help ensure their water supply. By 1900 thirty-eight farms and ranches had been established in Garza County and the population had risen to 185, but at the turn of the century the county's economy was still almost entirely devoted to cattle production. The agricultural census for 1900 reported only 545 improved acres in the county, with only twenty-one acres planted in corn, but the cattle herds that year comprised 29,094 head.
The development of the county quickly accelerated after 1906, when Charles William Post bought 250,000 acres in Lynn and Garza counties to start an experimental colony. He bought a number of ranches, fenced off the land in 160-acre tracts, laid out a townsite, built houses, and in other ways worked to attract settlers. In 1907 Garza County was formally organized, with the new town of Post City designated as county seat. Land speculators and liquor were banned in the settlement. That same year, Stockton Henry began publication of the Post City Post. By one estimate, more than 1,200 families followed the cereal millionaire to the colony, and the company town Post named for himself hastened the development of the entire region. Transportation improved with an extension southward through the county of the Panhandle and Santa Fe Railway in 1910.
C. W. Post sponsored a number of agricultural experiments in the area. His rainmaking efforts between 1910 and 1913 were some of the more colorful, if less conclusive, of these. Post's "rain battles," as he called them, involved the heavy use of explosives fired from kites and towers along the rim of the Caprock. Though more than half of the "battles" produced immediate measurable moisture, the project did not actually contribute to the colony's success in agriculture. Nevertheless, by 1910 there were eighty-one farms and ranches in Garza County, and the population had increased to 1,995; by 1920 farms and ranches numbered 425 and residents 4,253.
Though C. W. Post is and was best known for his cereal company, little corn or wheat was grown by the settlers he attracted to his colony: instead, cotton became the foundation of the area's agricultural economy. Post built a gin in 1909 and a cotton mill in 1911, and by 1920 cotton culture occupied almost 18,358 acres in Garza County; corn was planted on 1,389 acres, and wheat production was negligible. By 1925, 617 farms had been established; by 1929, the number was 796, and more than 51,100 acres in the county was planted in cotton. But the cotton boom peaked in the 1920s, and by the end of the decade poultry production was growing in importance. In 1929 county farmers reported more than 36,000 chickens and produced almost 112,000 dozen eggs. Meanwhile, cattle continued to play a significant role in the economy; in 1929 more than 24,000 cattle were counted in Garza County, and sorghum culture occupied more than 10,000 acres of county land.
Many of the county's residents suffered through the effects of the Great Depression and the Dust Bowl during the 1930s. Cotton production dropped significantly, and many farmers left their lands. By 1940 cotton was grown on only about 35,000 acres, and the number of farms in the county had dropped to 721. The discovery of oil in the area in 1926 helped somewhat to offset the worst effects of the depression. Although the area lost many farms during the 1930s, the county's population actually rose slightly during that time; in 1940, 5,678 people lived in Garza County.
Starting in the late 1940s, petroleum became more important. Production of crude totaled only 12,278 barrels in 1938 and 11,216 barrels in 1944. By 1948, however, it had increased to more than 2,577,700 barrels; more than 5,507,000 barrels were pumped in 1956, and more than 6,752,000 in 1978. By January 1991, 250,618,823 barrels of petroleum had been extracted in Garza County since 1926. The petroleum industry helped to diversify and stabilize the economy, which remains fundamentally agricultural. The most important county industries in the early 1980s were agribusiness, oil and gas extraction, and textile mills. In 1982, 94 percent of the county was devoted to ranching and farming, and about 11 percent was cultivated, with cotton, sorghum, wheat, and hay being the most important crops. About 22 percent of county workers were employed in manufacturing. In the mid-1980s Garza County produced an $18 million annual average income from agriculture, 60 percent from crops, mostly cotton and grains; the remainder came from cattle and hogs. About 14,000 acres of the county's farmland was irrigated.
Most of Garza County’s voters supported the Democratic presidential candidates in virtually every election from 1908 (the first year the area participated in a national election) through 1964; the only exception occurred in 1928, when Republican Herbert Hoover carried the area. The area’s political loyalties began to shift, however, in 1968, when Democrat Hubert Humphrey could win only a plurality of the county’s votes, and in 1972, when Republican Richard took the area with almost 70 percent of the total. Though Democrat Jimmy Carter was able to win in Garza County in 1976, the Republican presidential candidates carried the county in every election from 1980 through 2004.
U.S. Highway 84 and State Highway 207 cross the county north to south, and U.S. Highway 380 crosses west to east, , and the area is also served by the Burlington Northern Santa Fe Railroad. After the 1940s the population fluctuated, rising in the 1950s and 1970s but dropping during the 1960s and 1980s. The census counted 6,264 residents in 1950, 6,611 in 1960, 5,289 in 1970, 5,336 in 1980, and 5,143 in 1990. In 1990 Hispanics accounted for about 25 percent of the population.
The U.S. census counted 6,435 people living in Garza County in 2014. About 44.2 percent were Anglo, 48.3 percent were Hispanic, and 7.3 percent African American. Of residents age twenty-five and older, 70 percent had completed high school and 10 percent had college degrees. In the early twenty-first century agriculture, oil production, and hunting leases were important elements of the local economy. In 2002 the county had 246 farms and ranches covering 499,552 acres, 81 percent of which were devoted to pasture and 18 percent to crops. That year farmers and ranchers in the area earned $9,738,000; crop sales accounted for $6,291,000 of the total. Cotton, beef cattle, and hay were the chief agricultural products. More than 4,291,000 barrels of oil were produced in the county in 2004; by the end of that year 334,732,515 barrels of oil had been taken from county lands since 1926.
Post (population, 5,470) is the county’s seat of government and largest town; other communities include Justiceburg, Graham, Close City, and Pleasant Valley. The county offers visitors lake activities, scenic areas, the Post-Garza Museum, and Founders Day, which is held in September.