# USA - USGS 3DEP 1m Seamless DEM

> Seamless 1-meter Digital Elevation Models (S1M) from the USGS 3D Elevation Program (3DEP), distributed via USGS ScienceBase.

- **Collection ID:** `usa-usgs-3dep-1m-seamless`
- **Resolution:** 1 m
- **Products:** Digital Terrain Model (DTM)
- **Coverage:** 122.1°W to 66.8°W, 26.4°N to 47.5°N
- **Time range:** 1931 – 2025
- **Items indexed:** 11,285
- **License:** [CC0-1.0](https://spdx.org/licenses/CC0-1.0.html)
- **STAC JSON:** https://api.darly.io/collections/usa-usgs-3dep-1m-seamless

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:**
- [S1M product overview](https://www.usgs.gov/3d-elevation-program/new-product-3d-elevation-program-seamless-1-meter-digital-elevation-model-s1m)
- [ScienceBase record](https://www.sciencebase.gov/catalog/item/67af83c1d34e5020fb91f170)
- [USGS 3D Elevation Program](https://www.usgs.gov/3d-elevation-program)

## Providers

- [U.S. Geological Survey, 3D Elevation Program (3DEP)](https://www.usgs.gov/3d-elevation-program) (producer, licensor, host)
- [Darly](https://darly.io) (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.

## Access

```bash
curl "https://api.darly.io/collections/usa-usgs-3dep-1m-seamless/items?limit=5"
```

Browse it in the [Data Explorer](https://darly.io/explorer) or read the [STAC API docs](https://darly.io/docs/stac).