Sebastian is nine miles south of Raymondville on State highways 413 and 448 and the Missouri Pacific Railroad on the southern border of Willacy County. The community, settled before 1906, was first known as Stillman but was renamed Sebastian around 1912.
Sebastian. Originally part of the San Juan de Carricitos land grant, this townsite later was part of South Texas' famed King Ranch. Sebastian was known as Stillman Town Tract until 1906, when it was renamed to honor an officer of the Rock Island Railroad. In 1914, the Sebastian Realty Company was promoting the town in the hope that it would become a major agricultural center. During the early 20th-century period of lawlessness in South Texas, Sebastian experienced a bandit raid in which two members of the Austin family were killed. Historical marker text, 1985. Marker Location: At US 77 Bus. & FM 506, next to Post Office, Sebastian.
Sebastian Texas History from the Handbook of Texas Online.