Kingsbury is a city in northeastern Guadalupe County. Sam Neel, an agent for English settlers, built a home near the site in the early 1870s. The Galveston, Harrisburg and San Antonio Railway came through in 1875 and a post office was opened that year with Mark W. Isard as postmaster. The townsite was laid out in 1876 and named for railroad official William Kingsbury. By the mid-1880s the settlement had a steam gristmill, a cotton gin, a general store, a church, a district school, and a population of 130. In 1904 the population had risen to 346, and the town had two one-teacher schools for fifty-nine black students and two schools and three teachers for 123 white students. Kingsbury became part of the Seguin Independent School District in 1962. Cotton was the leading product of the area during the late nineteenth and early twentieth centuries; oil became important when the Gander Slu and Darst Creek oilfields came in during the 1920s. The estimated population reached 450 in 1968. Kingsbury had 200 residents and six businesses in 1990. Its economy was still largely based on oil and agriculture. By 2000 the population reached 652 with twenty-nine businesses.
Kingsbury was the setting of Dierks Bentley's music video of the song "What Was I Thinkin'".
As of the census of 2000, there were 652 people, 252 households, and 193 families residing in the CDP. The population density was 22.7 people per square mile (8.8/km²). There were 269 housing units at an average density of 9.3/sq mi (3.6/km²). The racial makeup of the CDP was 92.48% White, 1.84% African American, 0.46% Native American, 4.14% from other races, and 1.07% from two or more races. Hispanic or Latino of any race were 13.65% of the population.
There were 252 households out of which 32.1% had children under the age of 18 living with them, 60.7% were married couples living together, 11.9% had a female householder with no husband present, and 23.4% were non-families. 19.0% of all households were made up of individuals and 7.9% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 2.93.
In the CDP the population was spread out with 25.0% under the age of 18, 8.6% from 18 to 24, 29.4% from 25 to 44, 27.1% from 45 to 64, and 9.8% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 99.4 males. For every 100 females age 18 and over, there were 95.6 males.
The median income for a household in the CDP was $50,156, and the median income for a family was $60,536. Males had a median income of $38,750 versus $27,750 for females. The per capita income for the CDP was $21,744. About 4.3% of families and 8.7% of the population were below the poverty line, including 11.4% of those under age 18 and 9.6% of those age 65 or over.