Hays County is a county in the central portion of the U.S. state of Texas. It is part of the Austin-Round Rock metropolitan area. As of the 2020 census, its official population had reached 241,067. The county seat is San Marcos. Hays, along with Comal and Kendall Counties, was listed in 2017 as one of the nation's fastest-growing counties with a population of at least 10,000. From 2015 to 2016, Hays County, third on the national list, had nearly 10,000 new residents during the year.

Austin is the capital of the U.S. state of Texas, as well as the seat and most populous city of Travis County, with portions extending into Hays and Williamson counties. Incorporated on December 27, 1839, it is the tenth-most populous city in the United States, the fourth-most populous city in the state after Dallas, San Antonio and Houston, and the second-most populous state capital city after Phoenix, the capital of Arizona. It has been one of the fastest growing large cities in the United States since 2010. 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 million people. Austin is the southernmost state capital in the contiguous United States and is considered a Beta-level global city as categorized by the Globalization and World Cities Research Network.