San Marcos ( SAN MAR-kəs) is a city and the county chair of Hays County, Texas, United States. The city’s limits extend into Caldwell and Guadalupe Counties, as well. San Marcos is on the Interstate 35 corridor between Austin and San Antonio. Its population was 44,894 at the 2010 census and 67,553 at the 2020 census.
Founded on the banks of the San Marcos River, the area is thought to be accompanied by the oldest continually inhabited sites in the Americas. San Marcos is house to Texas State University and the Meadows Center for Water and the Environment.

In 2010, San Marcos was listed in Business Week‘s fourth annual survey of the “Best Places to Raise your Kids”. In 2013 and 2014, the United States Census Bureau named it the fastest-growing city in the United States. In December 2013, it was named number nine on Business Insider‘s list of the “10 Most Exciting Small Cities In America”.

Archeologists have found evidence at the San Marcos River allied with the Clovis culture, which suggests that the river has been the site of human habitation for higher than 10,000 years. The San Marcos Springs are the third-largest addition of springs in Texas. Never in recorded records has the river govern dry.

In 1689, Spaniard Alonso de Leon led an expedition from Mexico to consider Texas and state missions and presidios in the region. De Leon’s party helped blaze the Camino Real (later known as the Old San Antonio Road), which followed present-day Hunter Road, Hopkins Street, and Aquarena Springs Drive (the route far along shifted four miles to the south; it is now followed by County Road 266, known locally as Old Bastrop Highway). De Leon’s party reached the river on April 25, the feast morning of St. Mark the Evangelist; the river was suitably named the San Marcos.