ZIP Code 78666: San Marcos, TX
County: Hays
Coordinates: 29.87540, -97.94040
ZIP Type: Standard
Time Zone: Central Time (CT)
Get a reliable snapshot of the San Marcos, TX postal area 78666. This page summarizes county, coordinates, and local facts to help with services and location research.
| Primary City | San Marcos |
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| ZIP Code | 78666 |
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| County | Hays |
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| State | TX |
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| Latitude / Longitude | 29.87540, -97.94040 |
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| ZIP Type | Standard |
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| Time Zone | Central Time (CT) |
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| Data Updated | 2026-01-08 |
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Maps & Useful Links
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These links show the approximate center point for ZIP 78666 (not an exact boundary).
Geographic & Administrative Context
Coordinates for 78666 are listed as 29.87540 / -97.94040, useful for GPS and service checks in and around San Marcos, TX.
Local Coverage Notes
ZIP codes can cover multiple neighborhoods and unincorporated areas. Use ZIP 78666 for mail delivery and general location reference in
Hays,
TX.
Coverage may include nearby neighborhoods and adjacent unincorporated areas commonly associated with San Marcos.
Related ZIP Codes (Nearby)
Explore other postal codes near San Marcos within TX.
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Frequently Asked Questions
What is the primary city for ZIP code 78666?
The primary city for this ZIP code is San Marcos, located in TX.
In which county is 78666 located?
ZIP code 78666 is situated within Hays, TX.
What are the coordinates for 78666?
The approximate center point is 29.87540 (Latitude) and -97.94040 (Longitude).
Is ZIP code 78666 active?
This page lists ZIP 78666 as Listed based on the latest refresh date shown above.
Does ZIP 78666 cover multiple areas?
Yes. Many ZIP codes cover multiple neighborhoods or nearby areas. For exact boundaries, use official mapping tools.
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Methodology & Data Notes
How we build this page: We generate this page from a structured ZIP dataset and refresh key fields (city, county, and coordinates) during scheduled updates. Coordinates represent an approximate center point, not an official boundary map.
Sources: Public ZIP reference datasets and geographic coordinate references. If you use specific sources (e.g., USPS, Census), list them on your About/Methodology page.
Page updated: 2026-01-08