Seamless 1-meter Digital Elevation Models (S1M) from the USGS 3D Elevation Program (3DEP), distributed via USGS ScienceBase.
Source & method: Built from 3DEP-quality airborne lidar (Quality Level 2 or better). Individual 3DEP project DEMs are reprocessed into a single continuous bare-earth surface — seams between projects are removed, water-surface mismatches reduced, and the most recent / highest-quality lidar prioritized per tile. Voids larger than 10 m are backfilled with coarser (1/9 and 1/3 arc-second) DEMs; smaller voids are interpolated. This is a terrain (DTM) product.
Resolution: 1 m ground sample distance.
Coordinate reference: NAD83(2011) CONUS Albers (EPSG:6350); elevations in meters on NAVD88 (EPSG:5703, GEOID18). Per-item projection details are in each item's assets.
Coverage: Production began in 2025 and is ongoing — tiles publish as they become available, targeting the conterminous US, Hawaii, and Puerto Rico (Alaska excluded). Coverage is incomplete and grows over time.
Documentation:
Access
The catalog is browsable without a key. Elevation lookups need a free API key, sent as an X-API-Key header; see the quickstart.
curl "https://api.darly.io/collections/usa-usgs-3dep-1m-seamless/items?limit=5"curl -H "X-API-Key: $DARLY_API_KEY" \
"https://api.darly.io/v1/elevation/point?lat=36.99&lon=-94.45&collections=usa-usgs-3dep-1m-seamless"from pystac_client import Client
catalog = Client.open("https://api.darly.io")
search = catalog.search(collections=["usa-usgs-3dep-1m-seamless"], bbox=[-122.13, 26.45, -66.78, 47.53], max_items=5)
for item in search.items():
print(item.id, item.assets["dtm"].href if "dtm" in item.assets else item.assets["dsm"].href)Providers
- U.S. Geological Survey, 3D Elevation Program (3DEP) — producer, licensor, host
- Darly — processor
Citation
U.S. Geological Survey, 2025, USGS 3D Elevation Program Seamless 1-Meter Digital Elevation Model (S1M): U.S. Geological Survey data release, https://doi.org/10.5066/P13LJKFS.