What county is San Marcos, TX in?
Updated · Data: U.S. Census Bureau
San Marcos, Texas is in Hays County. San Marcos mailing addresses (ZIP codes named San Marcos) also reach Guadalupe County, so check your street.
San Marcos at a glance
How close is San Marcos to a county line?
The center of San Marcos (its Census internal point) is about 2.4 mi from the Caldwell County line. Homes near the edge of town can be much closer; if you live near a line, check your address and the lookup will tell you how far you are from it.
What ZIP codes are in San Marcos?
2 ZIP codes use the name San Marcos or are centered in it. Shares are of each ZIP's land; a ZIP named after a town can reach beyond its city limits.
| ZIP | Post office name | County (land share) |
|---|---|---|
| 78666 | San Marcos | Hays County 78%, Guadalupe County 16%, Comal County 4%, Caldwell County 2% |
| 78667 | San Marcos | Hays County |
About Hays County
County seat: San Marcos. FIPS code 48209. Population 256,429. All Hays County facts.
Towns near San Marcos
- Redwood: 4.7 mi away, Guadalupe County
- Martindale: 6.2 mi away, Caldwell County
- Kyle: 8.9 mi away, Hays County
- Uhland: 11 mi away, Hays County
- Wimberley: 12 mi away, Hays County
- Niederwald: 13 mi away, Hays County
San Marcos has about 68,920 people. It is an incorporated city or town.
Sources: ACS 2019-2023 5-year (residents by county, table B01003); Census TIGER/Line 2024 and Gazetteer 2024 (land, location); Census 2020 ZCTA file and GeoNames (ZIP codes). Data as of November 1, 2026. Not affiliated with any government agency.
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