Adjacent counties
- Cooke County (north)
- Grayson County (northeast)
- Collin County (east)
- Dallas County (southeast)
- Tarrant County (south)
- Wise County (west)
Early pioneers settled along the Trinity River and its tributaries and on the edge of the frontier as it moved westward. The first Anglo settlements were near Hebron in the southeast corner of what would become Denton County, Pilot Point in the northeast and Little Elm on the eastern border with Collin County.
Settlers were scarce, however, until the Republic of Texas approved an impresario grant in 1841 with the Texas Emigration and Land Company based in Louisville, Kentucky. W.S. Peters led the group of twenty investors, and the grant became known as the Peters Colony. The contracts eventually covered all of Northeast Texas. The colony's land office was established near Hebron in the southeast corner of present-day Denton County.
After Texas joined the union, promises of U.S. Army protection from marauding Indians prompted a new wave of immigration.
The new county, carved out of Fannin County, was named for John B. Denton, a pioneer preacher and lawyer who had been killed in an Indian fight in 1841. The pioneers chose a county seat along Pecan Creek and named it Pinckneyville, in honor of Texas' first governor. Historians differ on whether a courthouse was ever built at Pinckneyville. A 1908 history of the county describes a log courthouse built there, while another history says there were "no improvements" and court was held under a large oak tree.
Denton County covers 911 square miles in north central Texas. The Eastern Cross Timbers juts through the central part of the county. Blackland prairie covers its western half and a slice along its eastern edge. The Elm Fork of the Trinity River flows through the county. The river was dammed in 1920 to form Lake Dallas, which has been expanded and is now known as Lewisville Lake. The U.S. Army Corps of Engineers dammed the river farther upstream in 1986 to form Ray Roberts Lake. A greenbelt along the Elm Fork connects the two lakes. A number of state parks border the lakes.
Vital transportation links contributed more growth. Interstate 35 East was built in the 1950s and joined by Interstate 35 West in the 1970s. Dallas-Fort Worth International Airport opened in January 1974.
By the 1970s, Denton County was the fastest-growing county in the country, with most of the growth along the Interstate 35 East corridor. Denton County has ranked among the top fast-growing counties throughout the 1980s and 1990s. Population has spiraled from 75,633 in 1970 to 143,126 in 1980 to 276,083 in 1990 and 432,976 in 2000. Alliance Airport, which straddles the Denton County-Tarrant County boundary in the southwest corner of the county, opened in December 1989 to trigger growth along Interstate 35 West. Texas Motor Speedway, one of the largest sports and entertainment facilities in the world, opened in 1997 along Interstate 35 West.
The county population grew from 47,432 in 1960 to 143,126 in 1980. Many new rural residents owned small spreads, and mobile homes vied with expensive, sprawling ranchhouses for space. Large horse ranches were scattered through the county; in 1983 horses brought in $17,207,400, a significantly larger income than that from any other agricultural product (see HORSE AND MULE INDUSTRY). Newcomers and many older residents returned much of Denton County's rich cropland to pasture, and by the 1980s rural areas, almost depopulated by the rural-to-urban shift after World War II, had probably returned to their 1920s level in density of population.
Denton County voters supported Democratic candidates through 1948 with the exception of Herbert Hoover in 1928. From 1952 through 1992 they shifted their allegiance to the Republican party,qv again with only a single exception, Democrat Lyndon Baines Johnsonqv in 1968. In 1990 the population of Denton County was 273,525. The largest towns were Denton (66,270) and Lewisville (45,966 in Denton County). Attractions included Lewisville and Grapevine lakes, the annual Jazzfest held in September, and the North Texas State Fair in August.
By the end of the century, over 400,000 people were living in an increasingly urban Denton County. By the year 2000, the northern area of the county was a center for horse ranches and a balanced farming region producing wheat, cotton, beef and dairy cattle. Much of the industrial and commercial growth, as well as population growth, was centered in southern Denton County.
