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Brownsville, Texas
Inside Brownsville's city limits, shrink-swell clay limits houses without basements on 41% of mapped land. A shallow water table limits basements on 31%, the 5th-highest of 19 cities in Cameron County.
That clay share is above Cameron County's 29%. FEMA's flood data list 188 flood losses since 2016 in the 6 ZIP codes overlapping the city. Of its 64,878 homes, 30% were built before 1980; the median dates from 1995.
Data as of November 3, 2026 · sources · in Cameron County
expansive clay: shrink-swell limits slab homes
high water table: limits basements
flood losses since 2016 in 6 overlapping ZIPs
of homes built before 1980
Foundation repair in Brownsville
Foundation repair in Brownsville: shrink-swell clay limits slab homes on 41% of Brownsville's mapped land.
About 44,100 of Brownsville's 64,878 homes are detached houses.
| Who designs the repair | The ASCE Texas Section's repair guidelines say a Texas-licensed engineer should evaluate the foundation and design the repair (2022 guidelines) |
| Prices | Cost guide ranges compared |
Soil under Brownsville city limits
| Expansive clay (limits slab homes) | 40.7% |
| High water table (limits basements) | 31.3% |
| Septic fields very limited | 60.7% |
| Clay swell (LEP, by area) | 9.8% |
| High-swell land (LEP 6%+) | 42.9% |
| Urban land, not rated | 4.3% |
| Mapped soil | 82,376 acres |
| Soil series | Share here | Series nationally: expansive clay |
|---|---|---|
| Laredo | 27% | 0% |
| Lomalta | 14% | n/a |
| Olmito | 9% | n/a |
| Benito | 8% | n/a |
| Harlingen | 7% | n/a |
| Chargo | 6% | n/a |
What the numbers mean here
Clay swell averages a linear extensibility of 9.8% by land area here, and 43% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 41% of the mapped land.
Clay shrinks as it dries: 53.4% of Cameron County is in drought on the latest map, and 41% of Brownsville's mapped land has shrink-swell clay.
On 31% of Brownsville's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
USDA rates 61% of the land very limited for septic absorption fields.
Brownsville covers 122.1 square miles of land and counts 64,878 housing units, about 531 per square mile.
62% of Brownsville's occupied homes are owner-occupied, and the median owner-occupied home is valued at $139,900; 42% of all homes in the city date from 2000 or later.
The largest soil series under Brownsville is Laredo, on 27% of the mapped land, followed by Lomalta at 14%.
USDA's soil survey maps 82,376 acres inside Brownsville's city limits.
Drought in Cameron County
53.4% of Cameron County is in drought (D1 or worse) on the November 3, 2026 map. County detail.
Flood losses by ZIP code
FEMA flood records since 2016 in the ZIP codes that overlap Brownsville. ZIP areas reach past city limits.
| ZIP | Share of city land | Flood losses | Paid |
|---|---|---|---|
| 78526 | 25% | 38 | $597,959 |
| 78521 | 20% | 72 | $2.8 million |
| 78520 | 20% | 25 | $148,775 |
| 78578 | 14% | 22 | $239,676 |
| 78566 | 13% | 22 | $596,200 |
| 78575 | 2% | 9 | $12,467 |
Homes in Brownsville
| Housing units | 64,878 |
| Median year built | 1995 |
| Built before 1980 | 30% |
| Built 2000 or later | 42% |
| Owner-occupied | 62% |
| Median value, owner-occupied | $139,900 |
| Single-family detached | 68% |
Nearby cities
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Rancho Viejo | 6 mi | 26% | 5% |
| Los Fresnos | 6 mi | 45% | 10% |
| Indian Lake | 7 mi | 15% | 0% |
| Bayview | 11 mi | 27% | 3% |
| Port Isabel | 12 mi | 7% | 54% |
| Laguna Vista | 14 mi | 34% | 64% |
| San Benito | 14 mi | 63% | 4% |
| Los Indios | 16 mi | 41% | 1% |
Sources: USDA SSURGO (August 5, 2026) · US Drought Monitor (November 3, 2026) · FEMA NFIP v3 (September 9, 2026) · Census ACS 2020-2024. Methods · Data status