Decatur, the county seat of Wise County, is on U.S. highways 287 and 380 and the Burlington Northern Railway, forty miles northwest of Fort Worth at the approximate center of the county. It is near the western edge of the Grand Prairies, and overlooks the western Cross Timbers area. The Texas legislature established Wise County in 1856 and directed that a county seat named Taylorsville (in honor of Gen. Zachary Taylor) be founded within five miles of its center. The town was located and laid out by Absalom Bishop, an early settler in the region. Bishop, who was a member of the Texas Legislature, did not approve of Taylor's Whig party affiliation, and in January 1858 he arranged to change the name of the town to Decatur in honor of the naval hero Stephen Decatur.
The new community prospered in the years before the Civil War. A post office was opened in 1857 in the store of Daniel Howell, the town's first merchant and postmaster. The first school was established in the fall of 1857, and a courthouse was erected in the early 1860s. The Butterfield Overland Mail line served the community for several years before the war. As an exposed settlement on the Texas frontier, Decatur and its area stagnated during the war years and continued to suffer from Indian raids until 1874. Perhaps the most dramatic event of the war for the inhabitants of Decatur was the trial of members of the Unionist Peace party in the town and the execution of five of them in 1862 (see GREAT HANGING AT GAINESVILLE).
The late 1860s saw the establishment of four stores and a hotel in Decatur, which served as a supplier and market for local ranchers. The eastern fork of the Chisholm Trail passed near Decatur in this period and is commemorated by the town's annual Chisholm Trail Barbecue. In 1882 the Fort Worth and Denver Railway reached Decatur, and the gambler's cant phrase "eighter from Decatur" was coined, according to local tradition, by a railway construction worker. In the 1880s and 1890s Decatur prospered as a shipping point and market for local farmers, a prosperity that was reflected in the establishment of Decatur Baptist College in 1892, the building of a new courthouse in 1896, and a population that grew from 579 in 1880 to 1,746 in 1890. The town continued to grow in the early twentieth century, from a population of 1,562 in 1904 to a peak of 3,200 in 1928. Between 1929 and 1960 Decatur fluctuated between 2,000 and 3,000 inhabitants and remained an important business center of some eighty to 150 establishments. Decatur Baptist College was moved to Dallas in 1965. A steady growth in population after the 1960s is attributable in part to the influx of people who commute to Fort Worth. In 1990 Decatur had 4,252 residents; it was a center for petroleum production, clothing and glass manufacture, and marketing and processing for Wise County agribusiness. The population in 2000 was 5,201 and the community had 647 businesses.