Thorndale is an incorporated community on U.S. Highway 79 and Farm Road 486, twelve miles west of Rockdale in southwestern Milam County. It was established in 1878 about three miles west of its present site, shortly after the International-Great Northern Railroad was built through the area. A railroad employee named the town after the region's abundant thorny vegetation-mesquite thorn, prickly pear, and sagebrush. A post office, a store, and a hotel opened at Thorndale in the late 1870s. In 1880 the store was sold and moved east to the present site of the community on the railroad, and eventually the other businesses moved as well. By 1884 Thorndale had a church, a school, and 130 residents. The local economy was largely agricultural, and Thorndale served as a shipping and supply point for area farmers. In 1903 it had a two-teacher school for sixty-six students, and in 1913 the Thorndale Independent School District was formed. In 1929, the year in which Thorndale decided to incorporate, its population was reported as 1,500, but the onset of the Great Depression reduced the number of residents to about 1,000 by 1931, and it had fallen to 851 by 1952. During the mid-1950s, however, the population began to grow again, possibly because of the construction of an aluminum plant at nearby Sandow. For the next three decades the community grew steadily, and reported 1,338 residents and sixteen businesses in 1988. In 1990, however, its population fell to 1,092. The population was 1,278 in 2000.