- Slowest state
- 71%
- group D · Maine
- Slowest county
- 99%
- group D · Hendry County, FL
- Fastest county
- 98%
- group A · Thomas County, NE
The four soil groups
Engineers sort every soil into a hydrologic group by how fast water enters it when it is already wet: A (sand and gravel, fast), B (moderate), C (slow) and D (clay or a high water table, very slow). Soils listed as A/D, B/D or C/D would drain like the first letter if a high water table were lowered; here they count as D, because that is how they behave today.
States where rain soaks in slowest
Share of land in group D
| State | Group D | Group A | Group B |
|---|---|---|---|
| 1. Maine | 71% | 8% | 5% |
| 2. Florida | 66% | 22% | 4% |
| 3. Louisiana | 61% | 2% | 11% |
| 4. Illinois | 58% | 2% | 21% |
| 5. Ohio | 58% | 4% | 12% |
| 6. Indiana | 58% | 6% | 16% |
| 7. Minnesota | 57% | 10% | 12% |
| 8. Arkansas | 53% | 3% | 15% |
| 9. Michigan | 53% | 29% | 9% |
| 10. Missouri | 51% | 4% | 16% |
| 11. Vermont | 51% | 8% | 13% |
| 12. New York | 50% | 10% | 13% |
| 13. Nevada | 48% | 11% | 10% |
| 14. Alaska | 47% | 8% | 19% |
| 15. Iowa | 47% | 2% | 13% |
The 20 counties with the slowest soil
Share of land in group D
| County | Group D | Poorly drained | Most common soil |
|---|---|---|---|
| 1. Hendry County, FL | 99% | >99% | Oldsmar |
| 2. Van Wert County, OH | 98% | 95% | Pewamo |
| 3. Hyde County, NC | 98% | 89% | Pungo |
| 4. Tyrrell County, NC | 98% | 98% | Pungo |
| 5. Audrain County, MO | 98% | 96% | Mexico |
| 6. Baker County, FL | 98% | 98% | Pamlico |
| 7. Bay County, MI | 98% | 95% | Tappan |
| 8. Tipton County, IN | 98% | 93% | Patton |
| 9. Adams County, IN | 97% | 88% | Blount |
| 10. Blackford County, IN | 96% | 61% | Glynwood |
| 11. Jay County, IN | 96% | 57% | Glynwood |
| 12. Mercer County, OH | 96% | 84% | Blount |
| 13. Glades County, FL | 96% | 99% | Immokalee |
| 14. Ford County, IL | 96% | 94% | Ashkum |
| 15. Clinch County, GA | 96% | >99% | Surrency |
| 16. Hardin County, OH | 96% | 84% | Blount |
| 17. Paulding County, OH | 96% | 93% | Paulding |
| 18. Union County, OH | 96% | 81% | Blount |
| 19. Okeechobee County, FL | 95% | 98% | Myakka |
| 20. DeSoto County, FL | 95% | 99% | Smyrna |
The 15 counties where rain soaks in fastest
Share of land in group A
| County | Group A | Sandy topsoil | Most common soil |
|---|---|---|---|
| 1. Thomas County, NE | 98% | >99% | Valentine |
| 2. Hooker County, NE | 98% | >99% | Valentine |
| 3. Arthur County, NE | 96% | 98% | Valentine |
| 4. McPherson County, NE | 95% | 98% | Valentine |
| 5. Blaine County, NE | 94% | 97% | Valentine |
| 6. Grant County, NE | 93% | 94% | Valentine |
| 7. Cherry County, NE | 89% | 94% | Valentine |
| 8. Logan County, WV | 89% | 21% | Matewan |
| 9. Loup County, NE | 89% | 87% | Valentine |
| 10. Mingo County, WV | 87% | 20% | Matewan |
| 11. Logan County, NE | 85% | 82% | Valentine |
| 12. Crawford County, MI | 84% | 89% | Grayling |
| 13. Brown County, NE | 83% | 85% | Valentine |
| 14. Wheeler County, NE | 83% | 87% | Valentine |
| 15. Rock County, NE | 83% | 89% | Valentine |
What this means for a rain garden
A rain garden is a shallow planted bowl that catches roof and driveway runoff and lets it soak in within a day or two. It works with almost no effort on group A and B soils. On group C and D soils, make it larger and shallower, mix compost into the bottom, or choose plants that tolerate standing water, and test first: dig a hole, fill it with water, and see how long it takes to drain.
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. Hydrologic soil group is the NRCS group of each soil component, weighted by area; dual groups (A/D, B/D, C/D) count as D. Full methodology.