Kaufman County is located in northeastern Texas. Terrell, the county's largest town, is thirty miles east of Dallas. The county's center lies at approximately 32°35' north latitude and 96°18' west longitude. The county comprises 788 square miles of the Blackland Prairie region of Northeast Texas. The terrain is predominantly level to gently undulating, with an elevation ranging from 300 to 550 feet above sea level. The county is on the divide between two large rivers, the Trinity and the Sabine. It is located in the Trinity River watershed and is drained, in its western half, by the East Fork of the Trinity River and its tributaries, and, in its eastern half, by Cedar Creek and its tributaries, which flow into Cedar Creek Reservoir in the southern part of the county. Prairie grasses and mesquite, oak, pecan, and elm trees grow along the streams of the county. The soils are slightly acidic, with dark to light loamy surfaces and clayey subsoils. Mineral resources include limestone, sand and gravel, oil, and gas. The climate is subtropical-humid. Temperatures range in July from an average low of 72° F to an average high of 97° and in January from 33° to 54°. Rainfall averages thirty-nine inches, and the growing season averages 245 days each year.
Various Indians, Caddoes and Cherokees prominent among them, inhabited the territory that is today Kaufman County long before American settlers arrived. By the time of the coming of these first settlers, in 1840, the Cherokees had been driven by the Caddoes into East Texas. The Americans placated the Caddoes with jewelry and trinkets and consequently experienced few Indian problems. The first Kaufman County settlement was started in 1840 by William P. King and a group of forty pioneers from Holly Springs, Mississippi, who had purchased certificates for headrights from the Republic of Texas. The group built a fort and named it King's Fort in honor of their leader. Because of readily available land grants and because the land had been praised in eastern towns, the area around King's Fort, or Kingsboro, or Fort de Kingsboro, attracted settlers rapidly. On July 27, 1846, after the annexation of Texas by the United States, King patented the survey that included King's Fort with the new state government. The territory was at that time part of the recently organized Henderson County. Kaufman County was drawn from Henderson County, established in February 1848, and named for David Spangler Kaufman, a diplomat and member of the Congress of the Republic of Texas, the legislature of the state of Texas, and the Congress of the United States. King's Fort was renamed Kaufman and became the county seat in March 1851, after four elections. The county's northern boundary was reduced by the establishment of Rockwall County in 1873, and its limits have since remained unchanged. Kaufman County was settled predominantly by natives of the southern United States, particularly Tennessee, Arkansas, and Missouri. Though slaves were brought to the county, slavery was never widespread here, perhaps because cotton culture remained minimal until after the Civil War. The 1860 census counted 533 slaves (15 percent of the population).
In 1861, by a three-fourths majority, Kaufman County's citizens voted in favor of the state's secession from the Union. During the four years of the Civil War, the county contributed several companies of soldiers, most of whom fought in Elkanah B. Greer's regiment. In terms of actual combat, the war did not come to Kaufman County, although it was felt, as slave patrols were established in each precinct and the tax dollars of the citizens went to purchase supplies for county companies in the war and to arm the county. The end of the Civil War brought Reconstruction. Although the requirements of congressional Reconstruction were unpopular in the county, the period passed with few incidents of violence against either freedmen or White Unionists, perhaps because of the small Black population. Black citizens, however, found that freedom did not bring significant educational opportunities.
From 1880 to 1930 Kaufman County retained its antebellum rural and agricultural character. During this fifty-year period, the population almost tripled, growing from 15,448 to 40,905. The county's Black population more than doubled between 1880 and 1930, rising from 13 percent to 29 percent of the total. The number of farms more than tripled, rising from 1,594 to 5,131, the latter again an all-time high. Corn, which had been the county's main crop before the Civil War, continued a steady growth in production until 1910, when the harvest reached a high of 855,933 bushels; production declined thereafter, to 648,229 bushels in 1930. The county's cotton crop, which had shown steady growth since 1860, reached an all-time high of 57,698 bales in 1930, and wheat production, which had varied drastically since 1860, reached a maximum yield of 175,405 bushels in 1920. The number of beef and dairy cattle raised in Kaufman County, which had increased from 1860 to 1880, fell drastically between 1880 and 1890 and declined to a low of 950 beef cattle and 7,282 dairy cattle in 1930. By the late 1800s, Kaufman County enjoyed a relatively good transportation system. The Texas and Pacific Railway was completed through the northern part of the county in 1873, when it was linked with Longview to the east and Dallas-Fort Worth to the west. During the mid-1890s, the Texas-Midland Railroad was completed through Kaufman County to Garret in the south and Paris in the north. The T-M, which had been purchased by Hetty H. R. Green in 1892 and was run by her son, Edward H. R. Green, established its shops and offices in Terrell, thus bringing an important industry to the county. The nonagricultural economy expanded slowly from 1880 to 1930. Fifteen manufacturing establishments employed only 106 workers in 1930. In 1883 the county was chosen as the site of the state's second hospital for the mentally ill. In that year a state committee purchased a 655-acre site near Terrell, and in 1885, Terrell State Hospital was opened. The United States Department of Agriculture Extension Service developed as the result of an experiment begun in Kaufman County. In 1903 the USDA sent Seaman A. Knapp to advise Kaufman County cotton farmers on methods of combating the boll weevil, which was then spreading across Texas. The major result of Knapp's visit was the establishment of the nation's first privately owned and operated demonstration farm just north of Terrell.
The 1930s and 1940s witnessed significant changes in Kaufman County as the Great Depression and World War II affected its people. Farm value fell by 56 percent between 1930 and 1940, and the number of farms decreased by more than 1,800. Unemployment rose from 2 percent in 1930 to more than 16 percent in 1940. In 1935, 1,294 workers were on government relief in Kaufman County. By 1940, 947 workers were employed by government works programs, while 1,163 workers were unemployed. A Civilian Conservation Corps camp near Kaufman employed young men in soil-conservation and erosion-control projects, and the National Youth Administration maintained a machine shop in the town. The Work Projects Administration spent over $1 million in Kaufman County between 1935 and 1940 on road and bridge construction and various building programs. The Second World War ended the economic crisis but also brought a sizable emigration from the county. The population decreased slightly during the thirties, from 40,905 to 38,308, and the period from 1940 to 1950 saw it fall to 31,170. White population had increased a bit between 1930 and 1940, and Black population had decreased by approximately 9 percent. During the 1940s, however, White population declined by 7 percent and Black population fell by 8 percent.
The population trends begun during the depression and war years continued from 1950 to 1970. The number of residents in Kaufman County declined to a twentieth-century low of 29,931 in 1960. This figure reflected a slight decrease in White population, though the county's Black population remained almost unchanged. The number of farms also continued to decline, with over 1,600 fewer in existence in 1970 than in 1940. Agriculture, however, continued to occupy more than half of the workforce. Kaufman County became predominantly urban for the first time in 1960, when 56 percent of the population lived in Terrell, the largest town, or in Kaufman. The same statistics applied in 1970. At the time that urban growth was occurring, the number of factories was increasing and a rapidly growing workforce was involved in manufacturing. By 1975, 13 percent of workers were occupied in manufacturing. Among other nonagricultural occupations, no single industry was dominant. Retail trade employed 10 percent of the county's labor force, service industries slightly less.
As the population of Kaufman County and its agricultural production declined, there were other, more positive, developments. The growing importance of the automobile greatly affected transportation. In 1932 the county had 5,089 registered motor vehicles. By 1946 the total stood at 6,862. There were 8,700 automobiles registered in the county in 1956; by 1970 the number had risen to 11,969, and the county was served by U.S. highways 80 and 175, State highways 34 and 243, and Interstate Highway 20, the major route of traffic from Dallas to Shreveport. The Rural Electrification Administration brought electrical power to the farms and rural homes of the county. Beginning in 1938, the Kaufman County Electric Cooperative made electricity widely available to county residents. Slow advancement in the educational level of the county's population occurred after 1940. In 1940, 12 percent of those aged twenty-five or older were high school graduates. By 1970, 26 percent met this standard.
Developments in Kaufman County during the 1970s suggested that the downward trends of the years since 1930 were being reversed and that the upward trends of the 1960s were continuing. Population, which had begun to increase again by 1970, reached 39,029 in 1980, the highest figure since the Great Depression. Whites accounted for this increase, as their numbers grew to 8 percent over the 1970 level. The Black population continued to decline, as it had since 1960, reaching a low of 7,393 residents, the smallest Black population since 1900. The decrease in the number of farms continued. The value of agricultural property, however, rose dramatically, to more than $200 million. Nonagricultural economic pursuits, with the exception of oil and gas production and transportation and public-utilities employment, increased considerably over 1970 levels. Development along Interstate 20 and the eastward spread of Dallas pointed toward further commercial development in the county. Educational advancement continued. In 1980, 40 percent of residents aged twenty-five or older were high school graduates, and 10 percent were college graduates. The economy depended on agribusiness, varied manufacturing, and retail sales; the northwestern part of the county was increasingly tied into the growth of the city of Dallas. Kaufman County's population increased dramatically during the 1980s, rising to 52,220 by 1990.
The county voted solidly Democratic in every presidential election from 1848 to 1980, with the exception of the 1972 election, when it voted for Richard Nixon. Though Democrat Jimmy Carter carried the county in 1976 and 1980, during the late twentieth century the area began to trend Republican, as that party's presidential candidates took the county in every election from 1984 through 2004.
In 2014 the census counted 111,263 people living in Kaufman County. About 68 percent were Anglo, 10.7 percent were African American, and 18.8 percent were Hispanic. Almost 75 percent of residents age twenty-five and older were high school graduates, and more than 12 percent had college degrees. In the early twenty-first century various manufacturing and trade concerns, agribusiness, and tourism were key elements of the of the area's economy, and many residents commuted to Dallas to work. In 2002 the county had 2,438 farms and ranches covering 419,553 acres, 48 percent of which were devoted to crops, 43 percent to pasture, and 7 percent to woodlands. In that year local farmers and ranchers earned $30,038,000; livestock sales accounted for $23,523,000 of the total. Nursery crops, beef cattle, horses, goats, hogs, sheep, wheat, hay, sorghum, cotton, and oats were the chief agricultural products. The larger communities in the county included Terrell (population, 16,287); Kaufman (6,829), the seat of government; and Forney (16,943). Cedar Creek Reservoir and Ray Hubbard Lake provided recreational opportunities.