ZIP code 78666 is officially located in the state of Texas, primarily serving the city of San marcos. It falls under the administrative jurisdiction of Hays County. When planning mail delivery, logistics routing, or demographic research, 78666 operates within the Central Time (CT) timezone and supports the 823 area codes.
According to the latest US Census Bureau and American Community Survey (ACS) datasets, the total population residing within the 78666 ZIP Code Tabulation Area is approximately 6,423. Understanding local economics is critical for market analysis; the median household income in this postal area sits at $62,666.