Grayson County, in north central Texas, is bordered by the Red River and by Fannin, Collin, Denton, and Cooke counties. The county seat, Sherman, which lies approximately sixty-five miles north of Dallas, is part of the Sherman-Denison Metropolitan Statistical Area. The county's center point is at 33°40' north latitude and 96°40' west longitude. Grayson County, 934 square miles in area, has an elevation ranging from 600 to 800 feet and generally level terrain with some low hills. The northern part, which drains into Lake Texoma and the Red River, is characterized by acidic soils of the Post Oak Belt, with loamy or sandy surfaces. The southern areas, which drain to tributaries of the Trinity River, have blackland soils conducive to the growth of trees such as post oak, bois d'arc, elm, and walnut, as well as various types of grasses. Natural resources include limestone, oil and gas, bituminous coal, and sand and gravel. Grayson County is drained principally by Choctaw Creek and its two main tributaries, Post Oak and Iron Ore creeks. The county has an average annual precipitation of thirty-seven inches, temperatures ranging from an average low in January of 30° F to an average high of 96° in July, and a growing season that averages 227 days a year.
Various Caddo groups, including the Kichai, Ionis, and Tonkawa Indians, were the earliest known inhabitants of the area that became Grayson County. These Indians, agriculturalists who found the soils of the area suitable to their way of life, traded and negotiated with the Spanish and French, who moved up the Red River during the eighteenth century to establish trading posts. French and Spanish expeditions resulted in the initial settlements established in 1836–37 at Preston Bend on the Red River, at Pilot Grove in the southeastern part of the county, and at Warren. After the establishment and surveying of the Peters colony in the early 1840s, settlement of the region progressed rapidly. On March 17, 1846, Grayson County, named for Peter W. Grayson, attorney general of the Republic of Texas, was marked off from Fannin County. The legislative action also specified that the county seat be called Sherman. The naming of the county seat in honor of Gen. Sidney Sherman was apparently an effort to effect a compromise between supporters of Sherman, an anti-Houston Whig, and Grayson, a pro-Houston Democrat. Sherman has the distinction of being one of the few towns in the Lone Star State named by an act of the legislature.
By 1850 Grayson County had a population of 2,008, most of whom had come from Southern states. The census enumerated 186 slaves, used mainly by farmers and stockmen along the Red River and its tributaries to raise grains and livestock, cotton being a minor crop in the area until much later. Throughout the 1850s Preston Bend grew in importance, and the character of the county as a trading and market center gradually emerged. Preston Bend, a landing for passengers and freight in a rapidly developing river trade, was also the northern end of the Preston Road, the state's oldest trail, which extended from the river to south of Austin. Further impetus to county growth occurred with the designation of Sherman as a station on the Butterfield Overland Mail route in 1858. By 1860 Grayson County's population had grown to 8,184, a significant part of the increase having occurred after 1858.
The attitude of the county in 1860–61 toward the issue of secession was not consistent countywide. Although the 1861 election resulted in a vote of 901 to 463 to remain in the Union, Whitesboro in western Grayson County was also the scene of one of the earliest secessionist rallies in Texas. Fear of alleged Union sympathizers in five north central counties, including Grayson, resulted in the deaths of forty men in the Great Hanging at Gainesville in 1862. During the Civil War Grayson County men served the Confederate cause in various parts of the South, but the Eleventh Texas Cavalry, composed of many area recruits, was commissioned to capture the federal forts in Indian Territory north of the Red River. No armed conflict was involved in these captures. The frequent visits of William Clarke Quantrill's guerillas during the war years afforded county residents some anxious moments, but the area suffered neither invasion nor severe deprivation as a result of the war. The political instability and economic depression that characterized much of Texas in the Reconstruction era plagued Grayson County as well. The passing of cattle herds through the crossing at Preston Bend and a steadily developing river trade, however, provided much-needed income to the area.
From 1870 to 1880 settlement in North Texas flourished. The arrival of the Houston and Texas Central Railroad in Sherman and the Missouri, Kansas and Texas in Denison in late 1872 initiated a period of phenomenal growth and development for Grayson County. The population expanded from 14,387 in 1870 to 38,108 in 1880, an increase unparalleled in the entire history of the county. Numerous towns—including Denison, Van Alstyne, Howe, Whitewright, Pottsboro, and Tom Bean—sprang up as a result of the coming of the railroad to Grayson County. The number of farms increased 460 percent between 1870 and 1880, and since the railroads provided transport for produce, Grayson County soon became a milling and market center for surrounding areas. In 1876 Sherman had five flour mills and the largest grain elevator north of Dallas. By 1891 it had erected the largest cottonseed oil mill in the world at that time. Denison, founded by the railroad in 1872, also experienced significant expansion during this period; from 1890 to 1930 its population exceeded that of the county seat. Although manufacturing and milling interests steadily expanded, however, Grayson County remained predominantly agricultural. The number of farms in the county regularly increased, reaching a zenith of 5,762 in 1900. The same year marked the highest production of corn in the history of the county—3,681,640 bushels. Bumper crops of wheat and cotton were also noted, and commercial orchards flourished. Throughout the early years of the twentieth century Grayson County remained agricultural, its farms in 1910 comprising 553,527 of the county's 602,880 total acres.
The advent of the automobile effected significant changes in Grayson County. The first countywide road system, all gravel, was established in 1915, and by 1920 Grayson County had hard-surfaced roads. In 1926 county residents registered 12,314 automobiles, a number that increased to 14,501 in 1930 and 28,427 in 1950. By 1970 the number of registered vehicles had grown to 36,833, and the county had numerous state highways as well as U.S. highways 377, 75, 82, and 69.
Between 1920 and 1930 Grayson County experienced the only decennial population decrease in its history. Having increased steadily from 1850, county population reached 74,165 in 1920. By 1930, however, it had dropped to 65,843, and in spite of subsequent regular increases the 1920 total was not exceeded until the 1970 census enumerated 83,225. The agricultural and manufacturing sectors declined as Grayson County faced the traumas of the Great Depression and World War II. The number of farms decreased from 5,169 in 1930 to 4,296 by 1940. Unemployment rose from 6.9 percent in 1930 to 19.5 percent by 1940, and in 1935, 4,705 county residents were on relief. Federal agencies were at work in the county, however, during these years. The courthouse, destroyed by fire in the Sherman riot of 1930, was rebuilt in 1936 with Public Works Administration funds, and the Civilian Conservation Corps did extensive soil-conservation work throughout the area. In 1938 the Rural Electrification Administration brought electric power to rural Grayson County, and by 1944 the cooperative had 2,086 members. The number of members increased steadily thereafter, to 4,633 in 1954, 7,497 in 1964, and 12,197 in 1984.
In 1938 Congress authorized the construction of a dam and reservoir north of Denison to control the flooding of the Red River, generate electrical power, and provide irrigation. Lake Texoma, the reservoir, with a shoreline of 1,250 miles, was developed by the Department of the Interior and the National Park Service and remains a major recreation area and tourist attraction. The dam project was an economic boom to the county, as was the construction of Perrin Air Force Base in 1941. The blow to Grayson County's economy caused by the closing of the base in 1971 was tempered somewhat by the conversion of the facilities into an airport, one of three currently in operation, and an industrial complex. The Denison Dam Project and the construction of Perrin Field precipitated a period of expansion and development that subsequently characterized Grayson County as a whole. Although the sale of livestock and livestock products remained high throughout the 1940s and 1950s, the number of farms decreased at a rate commensurate with declines on state and national levels. The opening of the first oilfield in the county in 1930 heralded a business that became integral to the economy. Grayson County had produced 120 million barrels of oil by 1970 and in 1980 recorded an average annual income of $54,000,000 from oil, gas, and stone, as compared to $28,000,000 from agriculture. In 2000 more than 1,546,800 barrels of petroleum were produced in the county; by the end of that year more than 249,976,800 barrels had been produced in the area since 1930. During the 1970s and 1980s Grayson County emerged as a manufacturing and trade center, with 31 percent of its labor force in 1980 employed in manufacturing and 19 percent in wholesale and retail trade. The 1980 census showed that 60.5 percent of the population twenty-five years and over were high school graduates and 12.9 percent were college graduates. County population totaled 89,796 in 1980 and 95,021 in 1990.
County voting was solidly Democratic before the Civil War and after Reconstruction. The voters of Grayson County favored the Democratic candidate in virtually every presidential election from 1892 through 1976; the only exception occurred in 1928, when Republican Herbert Hoover took the county. In both 1952 and 1956 Dwight D. Eisenhower failed to carry the county, though his birthplace in Denison is the feature of the Eisenhower Birthplace State Historical Site. After 1980, when Republican Ronald Reagan took the county, the area began to trend Republican. Republican presidential candidates carried the area in virtually every presidential election from 1980 through 2004; the only exception was 1992, when independent candidate Ross Perot won a plurality of the county's votes.
In 2014 the census counted 123,534 people living in Grayson County. About 77.3 percent were Anglo, 6.1 percent were African American, and 12.2 percent Hispanic. More than 80 percent were high school graduates, and more than 17 percent had college degrees. By the early twenty-first century the area had become a distribution and trade center for north Texas and southern Oklahoma; manufacturing and agriculture were also important elements of the local economy. In 2002 the county had 2,597 farms and ranches covering 441,246 acres, 53 percent of which were devoted to cropland and 40 percent to pasture. In that year farmers and ranchers in the area earned $41,865,000; livestock sales accounted for $21,857,000 of the total. Beef cattle, wheat, nurseries and turf, forage, and horses were the chief agricultural products. In 2000 there were 35,082 people living in Sherman, the county's seat of government. Other towns include Denison (population, 22,979), Bells (1,407), Collinsville (1,618), Dorchester (149), Gordonville (165), Gunter (1,455), Howe (2,585), Knollwood (427), Luella (639), Pottsboro (2,215), Sadler (349), Southmayd (1,002), Tioga (820), Tom Bean (1,043), Van Alstyne (3,137), Whitesboro (3,853), and Whitewright (1,625). Austin College in Sherman and Grayson County Junior College midway between Sherman and Denison offer county residents varied educational opportunities. Several organizations, including the Old Settlers Association, pursue historic preservation and promote awareness of the history and development of Grayson County.