DeKalb is on the Missouri Pacific Railroad and U.S. Highway 82 twelve miles northwest of New Boston in western Bowie County. It was one of the earliest settlements in the county. According to some county histories a community had begun to take shape in the winter of 1835, when David Crockett visited the site on his way to the Alamo. These sources claim that when Crockett enquired about the name of the town, residents told him it had none and then asked him to name it. He suggested the name of the Prussian Baron de Kalb, a general of the American revolutionary army.
One purpose for founding the community was to establish a school. In fact, several of the early settlers were involved in the successful effort to get the Texas Congress to grant land for the establishment of DeKalb College in 1839. The school, however, seems to have been located several miles south of the community. Because DeKalb was supposed to serve as an educational focal point for surrounding farmers, the owners of the land attempted to restrict settlement to those they considered acceptable. As David Chisholm put it in 1837, "This town or village is situated on Browning's and my land, about one half mile from my house. This land is not to be sold to any Tom, Dick, or Harry to put up dram shops on, but for those who wish to have the river for health or the benefit of the school."
Despite the facts that DeKalb served as the first seat of Bowie County in 1841 and that it was on prime agricultural land, the town grew very slowly. One important cause was the lack of efficient, reliable transportation. When the Texas and Pacific Railway was built through the county in 1876, DeKalb became a station on the rail line and began to grow. By 1884 it had two churches, a school, a gin, a sawmill-gristmill, and a population of 200. By 1890 the town had a population of 500, a bank, and a weekly newspaper, the Flag, edited by L. A. Petit. Afterward, DeKalb grew slowly to a population of 1,023 by the 1930s.
In 1980 it had a population of 2,217. Agriculture remained of vital importance to the local economy, but, whereas cotton had been the dominant area crop during the nineteenth and early twentieth centuries, it had been replaced by vegetables, fruit, livestock, and hay. The town's businesses reflected that change. By the 1970s DeKalb was known for its cannery and its large shipments of tomatoes. Many of its residents were also employed at Red River Army Depot in eastern Bowie County. In 1990 the population was 1,976, and in 2000 it was 1,769.