San Marcos is the seat of Hays County and lies just northeast of San Antonio, above New Braunfels toward Austin along I-35 on the banks of the San Marcos River.
Among the 400 businesses recorded by 1980 were manufacturers of furniture, sheet metal products, plastics, woolens, lighting fixtures, telecommunication devices, baked goods, construction materials, and tortillas.
Austin's emergence as a regional metropolitan center is another cause of the remarkable growth of San Marcos since the 1950s; in 1973 Hays County and San Marcos became part of the Austin Standard Metropolitan Statistical Area. By the mid-1980s at least 20 percent of Hays County's labor force worked in Travis County. San Marcos itself was estimated to have a population of 25,000 and an additional 20,000 students, for a total of 45,000. In 1990 the population was 28,743.
It is part of the Austin-San Marcos, Texas metro area.