Find the last 4 digits (ZIP+4) for an address in 78666

ZIP 78666, San Marcos, TX is filled in. Just type the street address.

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ZIP Code 78666 – San Marcos, TX

San Marcos, Texas · Hays County · Central time

ZIP code78666
CitySan Marcos
StateTexas
CountyHays CountyGuadalupe CountyComal CountyCaldwell County
Population88,583
Time zoneCentral · local time
ZIP typeStandard (has a Census ZCTA area)
Land area192.36 sq mi
Center (lat, long)29.8817, -97.9848

Area codes in this area

512737

These are the area codes that most often serve ZIP 78666 (including overlays). The exact area code depends on the phone number — landlines, mobiles and overlays can differ even on the same street.

Map

Nearby ZIP codes

78655 Martindale · 10 mi78656 Maxwell · 10.7 mi78670 Staples · 11.5 mi78667 San Marcos · 12 mi78640 Kyle · 12.5 mi78130 New Braunfels · 13.9 mi78622 Fentress · 14.1 mi78623 Fischer · 14.8 mi

About ZIP 78666

ZIP code 78666 is assigned to San Marcos, Texas. It crosses 4 counties; most of its land is in Hays County. Its Census area covers about 192.36 square miles of land. The closest neighboring ZIP is 78655 (Martindale), about 10 miles away.

Every address in 78666 also has a 4-digit add-on code (ZIP+4) that points to a smaller delivery area. Use the box above to find it.

Sources: US Census Bureau (ZCTA, county relationship files), GeoNames (CC BY 4.0), NANPA via NumberResearch.org (CC BY 4.0). Map © OpenStreetMap contributors. ZIP areas are approximate. Population: U.S. Census Bureau, ACS 5-year estimates, 2024 (ZCTA). Data sources