Mission Valley, on Farm Road 236 fourteen miles northwest of Victoria, is the oldest community in Victoria County. Moving from their original location, probably on Garcitas Creek, Franciscan missionaries relocated Nuestra Señora del Espíritu Santo de Zúñiga Mission (La Bahía) and Nuestra Señora de Loreto Presidio at the site in 1726. Until forced to move to the area of present Goliad in 1749, the Franciscans operated the first great cattle ranch in Texas, in addition to farming and ministering to the local Aranama and Tamique Indians. Thereafter, the Spanish continued to ranch in the area, using Indian labor to raise thousands of cattle. In 1824 Mission Valley became one of the boundaries of Martín De León's colony on the Guadalupe, although the first recorded land grant in the county was made to a DeWitt colonist, Eben Haven, who settled in the locale in 1831. Félix De León, son of the empresario, was granted a league nearby two years later. Other notable pioneer residents of the Mission Valley vicinity included José María Carbajal , De León's surveyor general, who laid out the city of Guadalupe Victoria; Elijah Stapp, another DeWitt colonist and a signer of the Texas Declaration of Independence; and Margaret Wright, whom Sam Houston dubbed "Mother of Texas" for her role in the Goliad Massacre.
The Mission Valley community is on the old Indianola Trail to San Antonio, which supported much freight and cattle traffic before the railroads were built. A Mission Valley post office was established in 1854, and several churches were built in the community, as German and Anglo settlers continued to locate in the area, among them Gilbert Onderdonk, the horticulturist who operated Mission Valley Nurseries, and John Emison, the rancher who introduced the first blooded cattle to the county. The post office was removed in 1927. Grain and livestock continue to be the principal products, supplemented with oil and gas. The population estimate, which increased from sixty in 1914 to eighty-five in 1949, was 208 from 1974 to 1990. By 2000 the population was 225. Community centers in 1986 included Mission Valley School, part of the Victoria Independent School District, a Lutheran church, and a grocery. Evidence of the old Spanish settlement, including ruins of the mission, a concrete irrigation waterway, and two dams, was still visible, although on private property.