New Castle County, Delaware
New Castle County covers 426 square miles of land. Below is what the Isopleth API returned at the Census Bureau's interior point for the county (39.57592, -75.64413) on 2026-10-29. The ground sits at 13 m (41 ft) on a 5.8° slope, the mapped soil is well drained, it is outside a mapped FEMA floodplain, the nearest 69 kV+ substation is 2.3 km (1.4 mi) away and a major road is 507 m away. Values describe that one point, not the whole county; look up your own address or coordinates for your site.
Sample point values
| field | value | source |
|---|---|---|
| FEMA flood zone | X | FEMA_NFHL Federal Emergency Management Agencyvintage 10003C_STUDY2 |
| Inside a mapped floodplain | No | FEMA_NFHL Federal Emergency Management Agencyvintage 10003C_STUDY2 |
| Wildfire, annual frequency | 0.00044 events a year | FEMA_NRI Federal Emergency Management Agencyvintage December 2025 |
| Tornado, annual frequency | 0.0070 events a year | FEMA_NRI Federal Emergency Management Agencyvintage December 2025 |
| Hail, annual frequency | 2.2 events a year | FEMA_NRI Federal Emergency Management Agencyvintage December 2025 |
| On a mapped wetland | No | USFWS_NWI U.S. Fish and Wildlife Service |
| Nearest mapped wetland | 128 m | USFWS_NWI U.S. Fish and Wildlife Service |
| Elevation | 13 m (41 ft) | USGS_3DEP_COG U.S. Geological Surveyvintage 3DEP 1/3 arc-second seamless DEM |
| Slope | 5.8° | USGS_3DEP_COG U.S. Geological Survey |
| Soil drainage | Well drained | USDA_SSURGO U.S. Department of Agriculturevintage SSURGO DE003 mukey 2479822 |
| Soil hydrologic group | B | USDA_SSURGO U.S. Department of Agriculturevintage SSURGO DE003 mukey 2479822 |
| Farmland class | Statewide importance | USDA_SSURGO U.S. Department of Agriculturevintage SSURGO DE003 mukey 2479822 |
| Land use | Forest | USFS_LCMS USDA Forest Servicevintage USFS LCMS CONUS 2025 annual (30 m) |
| Crop or cover (CDL) | Grass/Pasture | USDA_CDL U.S. Department of Agriculturevintage USDA CDL 2025 (30 m) |
| Tree canopy | 16% | USFS_NLCD_TCC USDA Forest Servicevintage USFS/MRLC NLCD Tree Canopy Cover (latest annual, 30 m) |
| On protected land (PAD-US) | No | PAD_US USGS Protected Areas Database of the United States (PAD-US)vintage USGS PAD-US 4.1 (Protection Mechanism Category combined layer) |
| Surface manager | Private or unknown | BLM_SMA Bureau of Land Management |
| Annual precipitation (normal) | 1,179 mm (46 in) | NOAA_NCEI_NORMALS_GRIDDED National Oceanic and Atmospheric Administrationvintage NOAA NCEI 1991-2020 gridded (nClimGrid) monthly normals v1.0, annual layers |
| Days above 32 °C a year | 21 days | NOAA_NCEI_NCLIMGRID_DAILY National Oceanic and Atmospheric Administrationvintage NOAA nClimGrid-Daily v1.0 (scaled), 1991-2020 mean annual day counts |
| Solar resource (GHI) | 4.28 kWh/m²/day | NREL_SOLAR_RESOURCE_V1 NREL Solar Resource Data (NSRDB)vintage NREL PSM v3 multiyear annual average (1998-2016, ~4 km, Americas) |
| Mean wind speed at 100 m | 6.7 m/s | NREL_WIND_TOOLKIT NREL WIND Toolkit (Draxl et al., 2015)vintage NREL WIND Toolkit CONUS v1.0.0, 2007-2013 (5-min, 2 km) |
| Wind capacity factor | 35% | NREL_REV_LANDBASED_WIND_SC_2024 NREL reV supply curves, Open Energy Data Initiative (OEDI)vintage NREL reV land-based wind SC 2024 (Open access) |
| Nearest transmission line | 877 m | EIA_ATLAS U.S. Energy Information Administration |
| Nearest substation (69 kV+) | 2.3 km (1.4 mi) | EIA_POWER U.S. Energy Information Administration |
| Nearest gas pipeline | 193 m | EIA_ATLAS U.S. Energy Information Administration |
| Electric utility | DELMARVA POWER | EIA_POWER U.S. Energy Information Administrationvintage HIFLD Electric Retail Service Territories |
| In a public water service area | No | EPA_CWS_SERVICE_AREAS U.S. Environmental Protection Agencyvintage V3.0 (2026-03-17) |
| Depth to water, nearest monitored well | 9.4 m (31 ft) | USGS_NWIS_OGC U.S. Geological Surveyvintage USGS Water Data discrete groundwater-level field measurements (latest per well) |
| Nearest major road | 507 m | OVERTURE_TRANSPORTATION © Overture Maps Foundation, © OpenStreetMap contributorsvintage 2026-10-21.0 |
| Nearest FCC antenna structure | 1.3 km (0.8 mi) | FCC_ASR Federal Communications Commissionvintage FCC ASR weekly extract Sun Oct 25 06:21:42 EDT 2026 |
| Nearest fire station | 4.0 km (2.5 mi) | OVERTURE_PLACES © Overture Maps Foundationvintage 2026-10-21.0 |
| Nearest hospital | 6.9 km (4.3 mi) | OVERTURE_PLACES © Overture Maps Foundationvintage 2026-10-21.0 |
| Nearest school | 1.8 km (1.1 mi) | OVERTURE_PLACES © Overture Maps Foundationvintage 2026-10-21.0 |
| In an Opportunity Zone | No | HUD_OPPORTUNITY_ZONES U.S. Department of Housing and Urban Development |
Fields with no data at this point are left out. See the field catalog for all 351 fields.
Parcels
Parcel records: 454,607 parcels in 3 counties. New Castle County has 203,828 of them. Published by Delaware FirstMap; county governments (Public, attribution); Updated 2026-10-01, refreshed quarterly.
Not published here: owner name, site address, total value, land use, sale date, zoning, year built.
The parcel under the sample point is 538.3 acres. parcel_enrich returns that record for any parcel you ask about, and parcel_search finds parcels by acreage, land use or value.
Look up your own site
curl https://api.isopleth.dev/v1/fetch -H "Authorization: Bearer $ISOPLETH_KEY" \
-H "Content-Type: application/json" \
-d '{"lat": 39.575915, "lng": -75.644132, "preset": "site_selection"}'
Or ask your assistant through the MCP server: “Using Isopleth, check flood zone, wetlands, soils and distance to power for [your address in New Castle County, Delaware].”
Buying land here? Check the Land’s New Castle County page shows what its $29 report checks, built on these same Isopleth fields.
More in Delaware: Sussex County · Kent County · Delaware overview · all states