San Antonio–Austin metroplex in the context of "Austin, Texas"

San Antonio (/ˌsæn ænˈtoʊnioʊ/ SAN an-TOH-nee-oh; Spanish for "Saint Anthony") is a city in the U.S. state of Texas. It is the seventh-most populous city in the United States, second-most populous city in Texas and second-most populous city in the Southern U.S., with a population of 1.43 million at the 2020 census. The San Antonio metropolitan area, with an estimated 2.76 million residents, ranks as the third-largest metropolitan area in Texas and the 24th-largest in the nation. It is the county seat of Bexar County.

Founded in 1718 as a Spanish mission and colonial outpost, San Antonio became the first chartered civil settlement in present-day Texas in 1731. The city was named in 1691 by a Spanish expedition in honor of Saint Anthony of Padua. It was part of the Spanish Empire, then the Mexican Republic from 1821 to 1836, before joining the United States. Straddling the regional divide between South and Central Texas, San Antonio anchors the southwestern corner of an urban megaregion colloquially known as the Texas Triangle. It lies about 80 miles (130 km) from Austin along the I-35 corridor, and together the San Antonio–Austin metroplex is home to approximately 5 million people.

The Austin–Round Rock–San Marcos metropolitan statistical area, or Greater Austin, is a five-county metropolitan area in the U.S. state of Texas, as defined by the Office of Management and Budget. The metropolitan area is situated in Central Texas on the western edge of the American South and on the eastern edge of the American Southwest, and borders Greater San Antonio to the south. It forms part of the larger San Antonio-Austin Metroplex.

As of the 2020 U.S. census, the Austin–Round Rock–San Marcos MSA is the 26th-largest metropolitan area in the United States, with a total population of 2,352,426. The metropolitan area contains the city of Austin—the fourth-largest city in Texas and the 10th-largest city in the United States with a population of 974,447 people. Austin's largest suburbs are Round Rock, Cedar Park, Georgetown, San Marcos, Leander, and Pflugerville.

Greater San Antonio, officially designated San Antonio–New Braunfels, is an eight-county metropolitan area in the U.S. state of Texas defined by the Office of Management and Budget (OMB). The metropolitan area straddles South Texas and Central Texas and is on the southwestern corner of the Texas Triangle. The official 2020 U.S. census showed the metropolitan area's population at 2,558,143—up from a reported 1,711,103 in 2000—making it the 24th largest metropolitan area in the United States. Downtown Austin and Downtown San Antonio are approximately 80 miles (129 km) apart, and both fall along the Interstate 35 corridor. This combined metropolitan region of San Antonio–Austin has approximately 5.1 million people.

San Antonio–New Braunfels is the third-largest metro area in Texas, after Dallas–Fort Worth–Arlington and Houston–The Woodlands–Sugar Land.

Central Texas is a region in the U.S. state of Texas roughly bordered on the west by San Saba, to the southeast by Bryan-College Station, the south by San Marcos and to the north by Hillsboro. Central Texas overlaps with and includes part of the Texas Hill Country and corresponds to a physiographic section designation within the Edwards Plateau, in a geographic context.

Central Texas includes the metropolitan areas of: Killeen-Temple, Bryan–College Station, Waco and Austin–Round Rock (also part of the Capital region). The Austin–Round Rock and Killeen-Temple-Fort Hood areas are among the fastest-growing metropolitan areas in the state. In the south, the Greater Austin and Greater San Antonio areas are separated from each other by approximately 80 miles (129 km) along I-35. It is anticipated that both regions may form a new metroplex similar to Dallas-Fort Worth. The largest U.S. Army installation in the country, Fort Hood, is located near Killeen.