San Marcos, Texas
San Marcos is a Texas city whose current Census footprint includes Caldwell County, Guadalupe County, and Hays County. Start with the quick read below for what gives San Marcos its character, then the practical property-tax, insurance, district, and local-record checks worth making before you rely on a monthly estimate.
Place essentials
Official Census snapshot- Census place type
- City
- July 2025 population
- 77,830
- Change from 2020 base
- +14.9%
- Land area
- 40.4 sq. mi.
- County footprint
- Caldwell County, Guadalupe County, and Hays County
Place type, county footprint, and land area use the Census Bureau's January 1, 2025 geography. Population uses Vintage 2025 estimates through July 1, 2025; change compares that estimate with the April 1, 2020 estimates base. Geography file | Population file
Official routes
Use the office for the parcel address; a mailing city is not always the governing city.
Local checks
- Hays CAD account
- Flood zone / elevation certificate
- PID check (Trace, Whisper, Whisper South)
- School district (SMCISD vs. Hays CISD)
- Foundation / soil type (clay vs. limestone)
What buyers should know
Flood insurance is a real cost here, not an afterthought. Check the FEMA flood map for the specific parcel — the San Marcos River, Blanco River, and Purgatory Creek all have flood histories, and the 2015 Memorial Day event exceeded what FEMA maps predicted.
Know which side of the Balcones Escarpment your home sits on. West-side limestone lots behave differently from east-side clay lots; expansive clay is the main culprit behind foundation movement in the I-35 corridor and eastern neighborhoods, so a thorough pre-purchase foundation inspection is worth the cost.
San Marcos has seen some of the steepest appraisal increases in Texas due to rapid growth between Austin and San Antonio. Factor in potential year-over-year tax increases when budgeting, and check if the property carries a homestead exemption that will limit the increase after your first year.
County context
What to know around San Marcos
County lines carry much of the property, land, water, and outdoors context around San Marcos.
Oil History
Luling still wears its 1922 oil story in plain sight
Edgar B. Davis's 1922 discovery turned Luling into an oil boomtown, and decorated working pump jacks still carry that history through town.
Property Tax Basics
Two different offices handle your property taxes
Caldwell CAD appraises taxable property and collects local property taxes; the county Tax Assessor-Collector handles vehicles instead.
County History
How Guadalupe County Was Created
Guadalupe County was established in 1846, carved from parts of Bexar and Gonzales counties after Texas joined the United States.
Nearby places
Other local pages to compare
Nearby counties
Local notes for nearby counties
Next steps for San Marcos
Compare nearby places
Put Census population, land area, county footprints, and official office routes side by side.
Open comparison ->Estimate property tax
Use the official local rates and appraisal value for this parcel.
Open estimator ->Build a buyer timeline
Track homestead, appraisal notice, protest, and tax-bill dates.
Build timeline ->Read insurance guide
Check flood, windstorm, roof, deductibles, and coverage questions.
Read guide ->