ZIP Code 78666

ZIP code 78666 is a five-digit postal code used by the United States Postal Service for addresses in San Marcos, Texas. The ZIP lies within Hays County. Clocks here follow the America/Chicago time zone (UTC-5).

About 75,968 people live in this ZIP code, and the median household income is roughly $36,025 a year. Figures come from the U.S. Census Bureau American Community Survey and are refreshed as new five-year estimates are released.

What you can do with ZIP code 78666

• Write a mailing address: San Marcos, TX 78666. The ZIP goes last, after the state abbreviation.
• Check whether a shipping or delivery quote applies to this area — most US carriers price by ZIP code rather than by city.
• Look up the local time zone before scheduling a call — the ZIP tells you which zone applies to that address.
• Compare the ZIP with neighbouring codes to see how population and income shift block by block.