USGS S1M: A Seamless 1-Meter Elevation Layer for the United States

What the new Seamless 1-Meter DEM is, how it is organized, and how to actually pull it down and look at it.

By Randy George · Onterra Systems · June 2026

For two decades, the workhorse national elevation layer in the United States has been the 3DEP 1/3-arc-second DEM — roughly 10-meter ground sampling, seamless from coast to coast. It is dependable, but 10 meters smooths away the things that matter most at human scale: a road cut, a levee crest, a stream bank, the lip of a canyon. Meanwhile, the USGS has been quietly accumulating an enormous archive of 1-meter lidar-derived DEMs, project by project, county by county — thousands of individually-projected, individually-tiled rasters that were a genuine pain to assemble into anything continuous.

S1M — "Seamless 1-Meter" — is the USGS answer to that mess. It is a single, consistently gridded, nationally-tiled 1-meter elevation product, built to be mosaicked without the per-project bookkeeping. Production started in 2025 and is rolling out region by region. This post explains what it is, how the tiles are laid out, and how to grab one and render it. At the bottom are two live, embedded viewers: a 3D terrain model of the Tetons built from S1M, and an interactive index map of every tile published so far.

3D terrain of the Teton Range, rendered from a four-tile USGS S1M mosaic (Conus Albers → WGS84 → Terrain-RGB → MapLibre GL). Drag to orbit, scroll to zoom.

What S1M Actually Is

S1M is a 1-meter, bare-earth + surface elevation product distributed as 32-bit float GeoTIFFs. Each tile covers a tidy 10 km × 10 km square — that is 10,000 × 10,000 pixels at 1-meter sampling, which is why a single tile lands around 350–400 MB on disk. (If anyone tells you S1M is "1-arc-second, ~10 m," that is the old 3DEP product they are describing. The "1M" in the name is literal: one meter.)

The key word in the name is seamless. The underlying source lidar was collected in dozens of separate acquisitions, each in its own UTM zone and its own vintage. S1M re-grids all of it into one consistent national framework so that adjacent tiles butt up against each other exactly, with no projection seam, no resampling gap, and no overlap to reconcile.

How the Tiles Are Named and Organized

On the public S3 bucket, S1M lives under one prefix:

s3://prd-tnm/StagedProducts/Elevation/S1M/

Inside, tiles are grouped into 100 km blocks (e.g. n17e03/), and each block holds its individual 10 km tiles. A single tile directory looks like this:

StagedProducts/Elevation/S1M/n17e03/n1750e0340/
├── S1M_n1750e0340_20260616.tif    # the 1 m DEM  (~360 MB)
├── S1M_n1750e0340_20260616.jpg    # quick-look thumbnail
├── S1M_n1750e0340_20260616.xml    # ISO metadata
└── S1M_n1750e0340_20260616.gpkg   # tile footprint + stats

The tile id (n1750e0340) encodes the tile's position in the Albers national grid — an n northing component and an e/w easting component, block index followed by a 10 km offset. You rarely need to decode it by hand; the footprints are published as geometry (see the index map below), so you can just query by location.

The one file that ties it all together

There is a single GeoPackage at the top of the prefix that is worth knowing about:

StagedProducts/Elevation/S1M/FullExtentSpatialMetadata/S1M_Products.gpkg

It is about 5.6 MB and contains one polygon per published tile — the full national footprint index in a single download — with attributes for status, production date, elevation range, file size, and the S3 path to the GeoTIFF. It is a GeoPackage (just a SQLite database), so you can read it with GDAL, GeoPandas, QGIS, or even raw sqlite3. This is the fastest way to answer "what S1M exists right now, and where?" without crawling the bucket. The index map at the bottom of this post was built directly from it.

Three Ways to Access S1M

1. Browse the raw files (S3)

The public bucket listing lets you walk the prefix and pull individual .tif files directly — no account, no egress fee:

https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/S1M/

Useful for grabbing a known tile, but there is no spatial viewer here — you are reading directory names, not a map.

2. Query the footprint index

Download S1M_Products.gpkg once and query it offline. For example, to find every published tile near Jenny Lake with GDAL/OGR:

ogr2ogr -f GeoJSON near_jenny.geojson S1M_Products.gpkg \
  -dialect SQLite -sql \
  "SELECT tile, status, production_date FROM S1M_Products
   WHERE ST_Intersects(geom, BuildMbr(-110.8,43.7,-110.6,43.8))"

3. Render it on a web map

Because the DEM is Float32 elevation (not RGB imagery), to show relief on a slippy map you encode it into Terrain-RGB tiles and let MapLibre GL do the hillshading and 3D. That pipeline is exactly what produced the Tetons viewer below.

Where the S1M Tiles Are

The map below shows the four USGS S1M tiles that cover the Teton Range, drawn from their actual footprints in S1M_Products.gpkg. The red marker is Jenny Lake — it sits just inside the central (green) tile, right at the corner where all four tiles meet. Note the slight rotation of each square: these are 10 km tiles in CONUS Albers, so they tilt a few degrees once reprojected to WGS84. Hover or click each footprint to see the tile name and elevation range.

The four 10 km × 10 km S1M tiles mosaicked for the Tetons viewer, over Google Hybrid imagery (MapSavvy WMTS).

Each tile is a 10 km square in the S1M national grid. Together these four span roughly 43.66°–43.96°N and 110.92°–110.63°W — the full central Teton Range, from Buck Mountain up past Mount Moran:

A Worked Example: 3D Tetons from S1M

To turn S1M into the interactive 3D scene below, the recipe was:

1. Find the tiles. Query the footprint index for the bounding box around Grand Teton — four 10 km tiles cover the central range.
2. Mosaic them. gdalbuildvrt stitches the four GeoTIFFs into one virtual raster — fast and memory-light, no giant merged file.
3. Reproject to WGS84. gdalwarp -t_srs EPSG:4326. This is the non-negotiable step — skip it and the Albers coordinates put your terrain hundreds of miles off.
4. Encode & tile. Convert elevations to Terrain-RGB and cut an XYZ pyramid (zoom ~9–14), then point a MapLibre viewer at it with vertical exaggeration and a satellite basemap.

The imagery draped on top: MapSavvy WMTS

S1M gives you the shape of the land, but a bare elevation surface looks like gray clay. The photographic skin in the viewer above comes from MapSavvy, a commercial imagery service that re-serves Bing, Google, and HERE basemaps through a standard WMTS (Web Map Tile Service) endpoint. WMTS is the OGC standard for pre-rendered map tiles: you request a single tile by its {z}/{x}/{y} address and get back a 256×256 PNG, which is exactly the slippy-tile pattern MapLibre and Leaflet already speak. That makes MapSavvy a drop-in raster source — one URL template, no reprojection, no per-tile math.

Swap {layer} for GoogleHybrid, AerialWithLabels, GoogleTerrain, and so on, and the same terrain mesh gets a different skin. In the Tetons viewer the imagery layer selector does exactly this — it just rewrites the {layer} segment and tells MapLibre to refetch tiles. A WMTS service like MapSavvy is handy precisely because it hides the licensing and tiling differences between providers behind one consistent, web-mercator {z}/{x}/{y} interface, letting you focus on the elevation data rather than the basemap plumbing.

Where S1M Exists Today

S1M is a rollout in progress, not a finished national layer — there is no official public "availability viewer" yet. The map below is built straight from S1M_Products.gpkg: every rectangle is a published 10 km tile, colored by status. Coverage today is clustered — the Northeast corridor, Florida, the Midwest, and scattered Western projects — with new blocks added regularly as production continues. Click any tile for its name, production date, elevation range, and a direct download link.

Live S1M tile index — ~9,700 published 10 km tiles over OpenStreetMap, generated from the national footprint GeoPackage.

Why This Matters

A seamless 1-meter elevation layer changes what you can do at scale. Flood modeling that needs to resolve a levee or a culvert. Forestry and watershed work. Solar and rooftop analysis. Trail and corridor planning. Any of these previously meant hunting down individual lidar projects, reconciling UTM zones and vintages, and hand-stitching mosaics. S1M collapses that into "pick a bounding box, pull the tiles, mosaic, go." It arrives in Conus Albers and you will reproject for web use — but once you internalize that one quirk, it is the most usable high-resolution national elevation data the USGS has ever shipped.

Quick Reference

Tetons viewer and tile index built by Onterra Systems from public USGS 3DEP S1M data. Basemap © OpenStreetMap contributors.