San Marcos, Texas is the seat of Hays County. Located within the Austin–San Marcos metropolitan area, the city is located on the Interstate 35 corridor, between Austin and San Antonio. Founded on the banks of the San Marcos River, the area is considered to be among the oldest continuously inhabited sites in the Northern Hemisphere. San Marcos is home to Texas State University, and the Aquarena Center. Archeologists have evidence which suggests that the river has been the site of human habitation for more than 10,000 years. The headwaters of the San Marcos River are found in the middle of the city, and the springs, fed by the Edwards Aquifer are the second largest collection of springs in Texas. Never in human history has the river run dry.