Ranking · counties
The 25 US counties with the steepest land
The typical acre of Buchanan County, VA sits on a 65% slope, the steepest of any county. 15 of the 25 steepest counties are in West Virginia.
- Steepest county
- 65%
- typical slope · Buchanan County, VA
- Steepest state
- 30%
- typical slope · West Virginia
- West Virginia counties
- 15 of 25
- on the list
The 25 steepest counties
Typical slope of mapped land
| County | Typical slope | Steepest 10% above | Most common soil |
|---|---|---|---|
| 1. Buchanan County, VA | 65% | 65% | Shelocta |
| 2. Swain County, NC | 55% | 72% | Soco |
| 3. Wyoming County, WV | 53% | 58% | Berks |
| 4. Braxton County, WV | 53% | 53% | Gilpin |
| 5. Calhoun County, WV | 53% | 53% | Gilpin |
| 6. Clay County, WV | 53% | 53% | Gilpin |
| 7. Gilmer County, WV | 53% | 53% | Gilpin |
| 8. Lewis County, WV | 53% | 53% | Gilpin |
| 9. Mercer County, WV | 53% | 53% | Gilpin |
| 10. Roane County, WV | 53% | 53% | Gilpin |
| 11. Wetzel County, WV | 53% | 53% | Gilpin |
| 12. Kauai County, HI | 52% | 75% | Lihue |
| 13. Dickenson County, VA | 50% | 65% | Shelocta |
| 14. Boise County, ID | 50% | 60% | Shirts |
| 15. Boone County, WV | 50% | 58% | Matewan |
| 16. McCreary County, KY | 50% | 55% | Shelocta |
| 17. Martin County, KY | 50% | 55% | Shelocta |
| 18. Pike County, KY | 50% | 55% | Marrowbone |
| 19. Lincoln County, WV | 50% | 50% | Gilpin |
| 20. Logan County, WV | 50% | 50% | Matewan |
| 21. McDowell County, WV | 50% | 50% | Pineville |
| 22. Mingo County, WV | 50% | 50% | Matewan |
| 23. Wahkiakum County, WA | 48% | 78% | Lytell |
| 24. Lincoln County, OR | 48% | 70% | Bohannon |
| 25. Summers County, WV | 48% | 53% | Cateache |
States with the steepest land
| State | Typical slope | Flattest 10% below | Steepest 10% above |
|---|---|---|---|
| 1. West Virginia | 30% | 6% | 53% |
| 2. Idaho | 20% | 2% | 50% |
| 3. California | 19% | 1% | 55% |
| 4. Washington | 19% | 3% | 55% |
| 5. Hawaii | 15% | 4% | 55% |
| 6. Kentucky | 15% | 1% | 45% |
| 7. New Hampshire | 12% | 2% | 30% |
| 8. Oregon | 12% | 2% | 53% |
| 9. Pennsylvania | 12% | 2% | 43% |
| 10. Vermont | 12% | 4% | 43% |
Reading a slope percentage
Slope percent is the rise over the run: a 50% slope climbs 5 feet for every 10 feet across, about 27 degrees. Above about 15%, septic fields, driveways and foundations all get harder and more expensive; above about 25%, soil erosion becomes a constant concern and gardens usually need terraces.
Sources & data dates
- Source
- USDA NRCS Soil Survey Geographic Database (SSURGO), queried through Soil Data Access. Public domain.
- Data date
- SSURGO as published on November 3, 2026 (most recent survey area update October 26, 2026). NRCS refreshes SSURGO each October.
- Scope
- All mapped land in the 50 states and DC in the current soil survey.
- Method
- County rankings include counties with at least 100,000 acres of mapped land and soil ratings on at least 80% of it, so a small county with one unusual map unit cannot top the list. Counties without a full report on this site are named but not linked; the ZIP lookup covers them. Slope is each soil component's representative slope, as the area-weighted median for the county; ties are broken by the steepest 10%. Full methodology.