Seguin was founded in 1838 by members of Mathew Caldwell's Gonzales Rangers on land originally granted to Umphries (or Humphries) Branch by the Mexican government, but was not incorporated until 1853. Its original name was Walnut Springs but was changed just six months later to honor Juan Seguín.
Since 1912, Seguin has been the home of Texas Lutheran University.
Seguin is the location of the historic Wilson Pottery site; the first freed slave business in Texas. Seguin is also home to the Sebastopol House; built in 1856, it is a Texas Historical Commission Landmark and is in the National Register of Historic Places due to its unusual limecrete construction and architectural style. Another popular attraction is the Texas Agricultural Education and Heritage Center, where visitors may learn the mechanics and history of farming in the state of Texas.
Seguin is a large producer of pecans and is often attributed the nickname "Pecan Capital of Texas." The city boasts of having the "World's Largest Pecan," a five feet long, two-and- a-half feet wide concrete pecan located in front of the county courthouse. However, a similar pecan was built in Brunswick, Missouri in 1982 that is considerably larger.
Seguin is the setting of the 1994 Janice Woods Windle historical novel True Women and the 1997 CBS miniseries adaptation, True Women, starring Dana Delaney and Angelina Jolie. Seguin is where Nanci Griffith, the Grammy Award-winning singer, guitarist and songwriter, was born.
The main offices of the Guadalupe-Blanco River Authority are located in Seguin.
There were 7,526 households out of which 33.9% had children under the age of 18 living with them, 46.9% were married couples living together, 17.0% had a female householder with no husband present, and 30.4% were non-families. 25.9% of all households were made up of individuals and 12.8% had someone living alone who was 65 years of age or older. The average household size was 2.73 and the average family size was 3.29.
In the city the population was spread out with 27.4% under the age of 18, 13.3% from 18 to 24, 25.3% from 25 to 44, 18.7% from 45 to 64, and 15.3% who were 65 years of age or older. The median age was 33 years. For every 100 females there were 90.7 males. For every 100 females age 18 and over, there were 86.8 males.
The median income for a household in the city was $31,618, and the median income for a family was $36,931. Males had a median income of $27,007 versus $19,690 for females. The per capita income for the city was $13,740. About 13.2% of families and 17.2% of the population were below the poverty line, including 22.3% of those under age 18 and 13.6% of those age 65 or over.