Glen Rose, the county seat of Somervell County, is at the junction of U.S. Highway 67 and State Highway 144, on the Paluxy River in the central part of the county. The area was first settled in 1849 by Charles Barnard, who opened a trading post with his brother George Barnard near Comanche Peak. The Barnard brothers left the area in 1854 to operate a trading post on the Brazos Indian Reservation in present-day Young County. After the reservation was closed in 1859, Charles Barnard returned to the area and built the first store on what is now the site of Glen Rose. The next year he contracted with Milam County for a section of the land. County officials agreed to donate the title to him on the condition that Barnard build a flour and grist mill. He agreed, began construction on the mill, and named the town Barnard's Mill. The mill itself became a central part of community life; it served as a dance hall, as a meetinghouse, and in later years as the town hospital. By the 1980s it was listed in the National Register of Historic Places. In 1871 Barnard sold the mill to Maj. Tyler Calhoun Jordan of Dallas for $65,000. Popular tradition holds that Jordan's wife, Annie R. Lewis Jordan, suggested the name Rose Glen, because the scenic countryside reminded her of her native Scotland. However, census records indicate that she was born in Alabama. At a town meeting in 1872 residents agreed on the name Glen Rose rather than the alternative proposal. A post office was opened there in 1874, and Glen Rose became county seat of the newly formed Somervell County in 1875.
Though the county grew slowly, the town prospered. By the end of the 1800s it had several mills, three churches, two weekly newspapers, a school, a courthouse, a cotton gin, and the Glen Rose Collegiate Institute. The population of Glen Rose grew from 600 in 1890 to 1,000 in 1910. One reason for the town's prosperity was the abundant mineral springs in the area, which attracted numerous doctors and self-styled healers. Several sanatoriums were opened, and the town gained a reputation as a health and recreation center. Saloons and hotels advertised the waters of Glen Rose, which the United States Geological Survey of 1900 called "valuable for medicinal purposes." By the time of World War I the area's agricultural economy had begun to decline. Poor farming techniques allowed much of the shallow topsoil to wash away. A brief cotton boom after 1900 further depleted the soil, and cedar trees began to cover the rocky hillsides. During Prohibition the area was a center of moonshining, and the cedar brakes of Glen Rose became known as the "whiskey woods capital of the state."
Throughout the Great Depression the population of Glen Rose was reported as between 900 and 1,000. During the 1940s and 1950s, however, the county declined in population, as many residents moved in search of employment. Rural schools closed and consolidated with the Glen Rose educational district. But the population of Glen Rose remained stable at about 1,050 during the 1940s, then rose to 1,248 by the early 1950s. By the early 1980s it had increased to 2,075 and, by 1988, to 2,108. Much of the population increase in the 1980s was due to the construction of the nearby Comanche Peak Nuclear Power Plant, which began operation in 1981 and came to dominate the local economy. During the 1980s it was the largest employer in the county and the source of most of the county's tax revenue. At that time Glen Rose's other chief industries included farming, ranching, and tourism. Tourists who visited Glen Rose no longer came for its sulfur springs but to see the dinosaur tracks in Dinosaur Valley State Park, northwest of the town on Park Road 59. In the 1980s Glen Rose was also the home of John Graves, author of Goodbye to a River (1960), From a Limestone Ledge (1980), and other books; Graves has often been compared to Henry David Thoreau. The population of Glen Rose, an incorporated community, was reported as 1,802 in 1991, when the town had a post office, at least one bank, and 111 rated businesses. In 2000 the population was 2,122 with 224 businesses.