Henry County, Illinois
A shallow water table limits basements on 48% of Henry County's mapped land, a higher share than 64% of US counties. Shrink-swell clay limits houses without basements on 19%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 7 flood losses here since 2016. 79% of homes were built before 1980, against 50% nationally; the median home dates from 1961.
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 Henry County
| Expansive clay (limits slab homes) | 18.8% |
| High water table (limits basements) | 47.8% |
| Septic fields very limited | 61.3% |
| Clay swell (LEP, by area) | 4.3% |
| High-swell land (LEP 6%+) | 11.0% |
| Mapped soil | 528,120 acres |
How we count · survey areas IL073 (2025-08-31)
What the numbers mean here
Clay swell averages a linear extensibility of 4.3% by land area here, and 11% 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.
On 48% of Henry 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: 36.14 in, 2.07 in below the 1991-2020 average year of 38.21 in.
USDA rates 61% of the land very limited for septic absorption fields.
Drought
0% of the county is in drought (D1 or worse) on the October 13, 2026 map. Part of the county was in drought in 23 of the last 52 weeks; the most was 100% of its area, in 14 weeks, most recently on the March 31, 2026 map.
| Category, October 13, 2026 | Share of county |
|---|---|
| D0 abnormally dry or worse | 0% |
| D1 moderate drought or worse | 0% |
| D2 severe or worse | 0% |
| D3 extreme or worse | 0% |
| D4 exceptional | 0% |
Flood losses since 2016
7 flood losses since 2016, $82,296 paid. The worst year was 2017, with 4.
| Year | Flood losses |
|---|---|
| 2016 | 0 |
| 2017 | 4 |
| 2018 | 0 |
| 2019 | 0 |
| 2020 | 0 |
| 2021 | 0 |
| 2022 | 0 |
| 2023 | 1 |
| 2024 | 0 |
| 2025 | 0 |
| 2026 to date | 2 |
Rain
| Average year, 1991-2020 | 38.21 in |
| 12 months to August 2026 | 36.14 in (-2.07) |
| 2025 | 31.46 in (-6.75) |
| Wettest year since 1895 | 2019: 52.51 in |
| Driest year since 1895 | 2005: 20.94 in |
| Days with 1 inch or more, normal at GENESEO (7 mi away) | 9.5 |
Homes
| Housing units | 22,210 |
| Median year built | 1961 |
| Built before 1980 | 79% |
| Built 2000 or later | 8% |
| Owner-occupied | 80% |
| Median value, owner-occupied | $151,600 |
| Single-family detached | 87% |
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 |
|---|---|---|---|
| Rock Island County, IL | 24 mi | 6% | 32% |
| Stark County, IL | 25 mi | 36% | 52% |
| Knox County, IL | 29 mi | 41% | 41% |
| Whiteside County, IL | 30 mi | 2% | 40% |
| Bureau County, IL | 31 mi | 25% | 53% |
| Scott County, IA | 32 mi | 36% | 41% |
| Mercer County, IL | 33 mi | 15% | 44% |
| Warren County, IL | 43 mi | 35% | 54% |
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