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Mercer County, Pennsylvania
A shallow water table limits basements on 87% of Mercer County's mapped land, a higher share than 94% of US counties and the highest of 67 Pennsylvania counties. Shrink-swell clay limits houses without basements on 0%.
None of the county is in drought on the October 13, 2026 Drought Monitor map. FEMA's flood data list 15 flood losses here since 2016. 73% of homes were built before 1980, against 50% nationally; the median home dates from 1963.
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 Mercer County
| Expansive clay (limits slab homes) | 0.0% |
| High water table (limits basements) | 86.7% |
| Septic fields very limited | 97.3% |
| Clay swell (LEP, by area) | 1.8% |
| High-swell land (LEP 6%+) | 0.0% |
| Mapped soil | 436,723 acres |
| Soil series | Share here | Series nationally: high water table |
|---|---|---|
| Ravenna | 37% | n/a |
| Frenchtown | 17% | n/a |
| Canfield | 15% | over 99% |
| Chenango | 6% | n/a |
| Braceville | 3% | n/a |
| Halsey | 3% | n/a |
How we count · survey areas PA085 (2025-09-03)
What the numbers mean here
On 87% of Mercer 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: 43.05 in, 1.02 in below the 1991-2020 average year of 44.07 in.
USDA rates 97% 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 2 of the last 52 weeks; the most was 9.4% of its area, on the October 14, 2025 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
15 flood losses since 2016, $81,677 paid. The worst year was 2017, with 7.
| Year | Flood losses |
|---|---|
| 2016 | 1 |
| 2017 | 7 |
| 2018 | 0 |
| 2019 | 5 |
| 2020 | 0 |
| 2021 | 1 |
| 2022 | 0 |
| 2023 | 0 |
| 2024 | 1 |
| 2025 | 0 |
| 2026 to date | 0 |
Rain
| Average year, 1991-2020 | 44.07 in |
| 12 months to August 2026 | 43.05 in (-1.02) |
| 2025 | 41.42 in (-2.65) |
| Wettest year since 1895 | 2011: 56.70 in |
| Driest year since 1895 | 1963: 29.21 in |
| Days with 1 inch or more, normal at JAMESTOWN 2 NW (18 mi away) | 8.4 |
Homes
| Housing units | 50,930 |
| Median year built | 1963 |
| Built before 1980 | 73% |
| Built 2000 or later | 10% |
| Owner-occupied | 72% |
| Median value, owner-occupied | $164,000 |
| Single-family detached | 75% |
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 |
|---|---|---|---|
| Lawrence County, PA | 22 mi | 1% | 67% |
| Venango County, PA | 26 mi | under 1% | 73% |
| Trumbull County, OH | 27 mi | under 1% | 77% |
| Crawford County, PA | 28 mi | 0% | 85% |
| Butler County, PA | 32 mi | 1% | 53% |
| Mahoning County, OH | 34 mi | 9% | 77% |
| Beaver County, PA | 43 mi | 6% | 35% |
| Clarion County, PA | 44 mi | under 1% | 50% |
Sources: USDA SSURGO (September 3, 2025) · US Drought Monitor (October 13, 2026) · FEMA NFIP v3 (September 9, 2026) · NOAA (August 2026) · Census ACS 2020-2024. Methods · Data status