78666 is zip code located in San Marcos, Texas. The population is 63,255, making 78666 the largest zipcode in San Marcos and the largest in Hays County.
There are 14 public schools in 78666 with an average Homefacts rating of C+. The total crime rate for San Marcos is high , and there are 136 registered sex offenders residing in the zip code 78666. Unemployment in 78666 is moderate.