Alexander County, Illinois
A shallow water table limits basements on 48% of Alexander County's mapped land, a higher share than 65% of US counties. Shrink-swell clay limits houses without basements on 19%.
24.1% of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 49 flood losses here since 2016, 42% of them in buildings with basements. 70% of homes were built before 1980, against 50% nationally; the median home dates from 1969.
Data as of October 13, 2026 · sources
expansive clay: shrink-swell limits slab homes
high water table: limits basements
in drought, October 13, 2026
of homes built before 1980
Soil under Alexander County
| Expansive clay (limits slab homes) | 19.1% |
| High water table (limits basements) | 48.0% |
| Septic fields very limited | 82.0% |
| Clay swell (LEP, by area) | 4.8% |
| High-swell land (LEP 6%+) | 22.7% |
| Mapped soil | 163,270 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Stookey | 11% | n/a |
| Darwin | 7% | n/a |
| Menfro | 7% | 0% |
| Clarksville | 6% | 0% |
| Karnak | 5% | n/a |
| Riley | 4% | n/a |
How we count · survey areas IL003 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.8% by land area here, and 23% of the land reaches USDA's high class (6% or more). Clay like that swells when wet and shrinks when dry, under 19% of the mapped land.
Clay shrinks as it dries: 24.1% of the county is in drought on the latest map, and 19% of Alexander County's mapped land has shrink-swell clay.
On 48% of Alexander County's mapped land, soil stays saturated within about 6 feet of the surface for part of the year, which is basement depth.
Rain over the 12 months to August 2026: 42.28 in, 6.85 in below the 1991-2020 average year of 49.13 in.
USDA rates 82% of the land very limited for septic absorption fields.
Drought
24.1% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 20 of the last 52 weeks; the most was 100% of its area, in 10 weeks, most recently on the June 2, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 85.2% |
| D1 moderate drought or worse | 24.1% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
49 flood losses since 2016, $762,821 paid. The worst year was 2019, with 27. Foundations of the buildings, where recorded: 42% basements, 4% slabs, 38% crawl spaces, 17% elevated. Median water depth outside the building: 6 in.
| Year | Flood losses |
|---|---|
| 2016 | 8 |
| 2017 | 2 |
| 2018 | 0 |
| 2019 | 27 |
| 2020 | 2 |
| 2021 | 0 |
| 2022 | 1 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 1 |
| 2026 to date | 7 |
Rain
| Average year, 1991-2020 | 49.13 in |
| 12 months to August 2026 | 42.28 in (-6.85) |
| 2025 | 51.83 in (+2.70) |
| Wettest year since 1895 | 2011: 70.52 in |
| Driest year since 1895 | 1930: 29.94 in |
| Days with 1 inch or more, normal at CAPE GIRARDEAU MUNI AP (12 mi away) | 13 |
Homes
| Housing units | 2,938 |
| Median year built | 1969 |
| Built before 1980 | 70% |
| Built 2000 or later | 13% |
| Owner-occupied | 78% |
| Median value, owner-occupied | $59,800 |
| Single-family detached | 77% |
What repairs cost
Published ranges from cost guides, not quotes. More sources, and where they disagree.
Nearby counties
| Place | Distance | Expansive clay | High water table |
|---|---|---|---|
| Pulaski County, IL | 12 mi | 10% | 72% |
| Scott County, MO | 15 mi | 16% | 58% |
| Ballard County, KY | 21 mi | 2% | 67% |
| Union County, IL | 22 mi | 10% | 49% |
| Cape Girardeau County, MO | 23 mi | 3% | 24% |
| Mississippi County, MO | 25 mi | 33% | 85% |
| Carlisle County, KY | 31 mi | 3% | 72% |
| Johnson County, IL | 32 mi | 2% | 78% |
Sources: USDA SSURGO (August 31, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status