San Marcos city, Texas
Official LSAD Designation: San Marcos city • Census GEOID: 4865600
• Caldwell County / Guadalupe County / Hays County
Demographics & Population Profile
Population and demographics for San Marcos city.
| Demographic Variable | Estimate / Count | Margin of Error | Period | Source |
|---|---|---|---|---|
| Total Population (2025 PEP Estimate) | 77,830 | — | 2025 | Census |
| Median Age | 25.5 yrs | ±0.4 | 2020-2024 | Census ACS 5-Year 2024 |
| Total Households | 28,013 | ±869 | 2020-2024 | Census ACS 5-Year 2024 |
Source: U.S. Census Bureau (PEP, ACS 5-Year).