Seguin, the county seat of Guadalupe County, is on Interstate Highway 10 and the Guadalupe River, thirty-five miles northeast of San Antonio in the central part of the county. The land is suited for agriculture and ranching and is rich in oil and minerals. The Guadalupe River, the San Marcos River, and two major creeks, Cibolo and Geronimo, flow through the region. Archeological finds in the vicinity include the remains of mammoths east of Seguin and numerous Indian campsites along the Guadalupe River and various creeks in Guadalupe County. The first recorded evidence of exploration in the Seguin region was in 1718, when Martín de Alarcón, governor of the province of Texas, founded San Antonio de Béxar Presidio and San Antonio de Valero Mission in San Antonio and conducted several explorations north and east of San Antonio. Eventually Spanish, Mexican, and Anglo settlements were founded in the area that would become Seguin, where Tonkawa Indians had lived, and by 1833 there were forty land titles in the region. One of the most notable settlements was the ranch of José Antonio Navarro, three miles north of Seguin at a site now on State Highway 123. The next record of settlement in the Seguin region dates from 1831, when Umphries (or Humphries) Branch was awarded a league of land on the northeast bank of the Guadalupe, thirty-eight miles above Gonzales. In 1833 Branch and his family built a cabin, said to be the first Anglo residence on the site of what is now Seguin. The location chosen was in the western part of what had been Green Dewitt's colony, where Gonzales was the main town. Branch was assisted by his father-in-law, John Sowell. On August 12, 1838, thirty-three of the Gonzales Rangers, a volunteer group, joined Joseph S. Martin in laying out a townsite near Walnut Branch; they named the site Walnut Springs. The name was changed in February 1839 to Seguin for Juan N. Seguín.
During the Republic of Texas era, Seguin citizens petitioned to have the area made a county, and the Congress of the Republic of Texas responded by establishing Guadalupe County in 1842. This county was apparently never organized, however, because in March 1846, after the annexation of Texas, the new state legislature demarked a new Guadalupe County from Gonzales and Bexar counties. A post office was opened in Seguin in 1846. The first county judge was Michael H. Erskine. Seguin became the county seat of Guadalupe County and was governed by the county until it was incorporated on February 7, 1853, by a charter. The first acting mayor was John R. King, and the first elected mayor was John D. Anderson. Early on Seguin had Methodist, Presbyterian, Episcopalian, Catholic, and Baptist congregations. It chartered its first school in 1849, and the first schoolhouse was built in 1850 by John E. Park, inventor of Park's concrete. The schoolhouse, formerly known as Guadalupe High School and in the 1980s still used by St. James Catholic Church, was recognized by the state in 1962 as the oldest continuously used school building in Texas.
The foundation for Black education in Seguin and throughout Guadalupe County was largely the work of Black Baptists, aided by Rev. Leonard Ilsley and Rev. William Baton Ball. The first schools for Blacks were held in Methodist and Baptist churches. When the state adopted a community-based system of public education in 1876, Black residents organized the Abraham Lincoln School, which was renamed Ball High School in 1925. Guadalupe College, a school for Blacks, opened in 1887 and continued until 1936, when it was destroyed by fire. In 1912 Texas Lutheran College (now Texas Lutheran University) moved from Brenham to the Louis Fritz Farm near Seguin. Throughout the twentieth century the college remained an accredited, private, four-year liberal-arts institution that enjoyed distinction in sports and academics, and in 1996 the school became Texas Lutheran University.
The economy of Seguin has generally been agricultural, though in its early years the town was a trading partner of Gonzales, New Braunfels, and San Antonio. Seguin was on the trail taken by German emigrants from Indianola to the Hill Country. With the influx of the German population, farming methods improved and trade increased. By the time of the Civil War Seguin residents were growing cotton, corn, and peanuts and raising hogs and cattle. While the men fought in the Civil War the women, children, and older men tended to the farms and businesses. After the war Seguin was occupied by Union soldiers. One of its leading citizens, John Ireland, became governor of Texas and served from 1883 to 1887.
The Seguin economy improved dramatically in the late 1920s, when oil was discovered in the Darst Creek fields fifteen miles east of town. The community continued to be well-represented in the state government. State Senator Ferdinand C. Weinert of Seguin was responsible for long-lasting prison reforms and also worked to establish the Pasteur Institute of Texas, which saved many lives in the treatment of rabies. Hilda Blumberg Weinert's contributions to education and politics in Texas were also important. As the twentieth century progressed Seguin attracted manufacturing and service-oriented industries to diversify its agricultural and oil-based economy. In 1986 the Seguin city government changed from the mayor-council form of city government to the council-manager form of city government. By 1988 the town had an estimated population of 22,000 and more than thirty businesses that employed more than fifteen full-time workers each. By that year also the county hospital had expanded to seventy-five beds. The Seguin-Guadalupe County Library continued its expansion to more than 50,000 volumes, and the Seguin Gazette-Enterprise celebrated its centenary year in 1988. On August 12, 1988, Seguin celebrated its sesquicentennial year. Tourists were attracted to Max Starcke Park, the Guadalupe County Coliseum, and the County Fairgrounds, where the Texas State High School Rodeo has been held since 1984. The town boasted a number of antebellum homes, including the Sebastopol House State Historic Structure, and the greater Seguin area was the setting for author Janice Woods Windle's successful novel True Women (1993), featured in a television miniseries in 1997. In 2000 Seguin had a population of 22,011 and 1,338 businesses.