San Augustine is a city in Deep East Texas and the county seat of San Augustine County, about twenty miles west of the Texas-Louisiana border. At the 2020 census its population was 1,920. The county, organized in 1836 and named for Augustine of Hippo, lies entirely within the rural Piney Woods, bordered by the Attoyac River on the west, Sabine County on the east, Shelby County to the north, and Sam Rayburn Reservoir to the south. The area's history is among the oldest in Texas. Spanish missionaries established Mission Nuestra Señora de los Dolores de los Ais in 1717, marking the first European settlement in the region. The mission was re-established in 1721 and operated until 1773, serving the Ais people and other Native communities. Today the site is preserved as Mission Dolores State Historic Site, a 36-acre property with archaeological resources listed on the National Register of Historic Places that documents the encounter between the region's first European settlers and its indigenous peoples. San Augustine remains a working county seat, with county government, timber, and agriculture anchoring the local economy. The city is served by San Augustine Independent School District, a small rural district of roughly 600 students. Recreation centers on the outdoors: Sam Rayburn Reservoir, one of the largest lakes in Texas, offers fishing, boating, and camping, with Townsend Park providing a developed lakefront area, while the surrounding national forests and river bottoms support hunting and other pursuits. For those drawn to East Texas history, pine-forest living, and easy access to a major reservoir, San Augustine offers a distinctive, unhurried address near the Louisiana line.