# Geographic imagery and terrain

NASA Blue Marble: Next Generation, July 2004 land surface composite. NASA Earth Observatory / NASA Goddard Space Flight Center. Reprojected to the atlas's Albers USA layout, clipped to state outlines, and brightened. This is a historical composite, not live imagery or a formal land-cover classification.
https://science.nasa.gov/earth/earth-observatory/blue-marble-next-generation/base-map/

Mapzen Terrain Tiles, accessed September 6, 2026 through the public AWS terrain-tiles dataset, Terrarium format, zoom 5 for the national atlas and zoom 8 for 61 park close-ups. Resampled to a generalized atlas grid and rounded to 10 metres. Heights are vertically exaggerated and elevations below sea level are clamped to the base. The park close-ups use 257×257 elevation grids; the surface imagery retains its regional resolution. Small features and exact summit heights are not resolved. American Samoa and Virgin Islands use inset boundary views rather than these local elevation grids.
https://registry.opendata.aws/terrain-tiles/

* United States 3DEP (formerly NED) and global GMTED2010 and SRTM terrain data courtesy of the U.S. Geological Survey.
* Global ETOPO1 terrain data U.S. National Oceanic and Atmospheric Administration.
* ArcticDEM terrain data DEM(s) were created from DigitalGlobe, Inc., imagery and funded under National Science Foundation awards 1043681, 1559691, and 1542736.
* Canada terrain data contains information licensed under the Open Government Licence – Canada.
* Mexico terrain data source: INEGI, Continental relief, 2016.

Full provider attribution and data-source information:
https://github.com/tilezen/joerd/blob/master/docs/attribution.md
https://github.com/tilezen/joerd/blob/master/docs/data-sources.md

Park outlines: National Park Service boundary data hosted by the National Park Service ArcGIS organization, downloaded September 6, 2026. Simplified with a 0.003-degree tolerance. Administrative outlines do not imply public ownership of every parcel or permission to enter. Park and preserve boundaries follow the source dataset.
https://services1.arcgis.com/fBc8EJBxQRMcHlei/ArcGIS/rest/services/National_Park_Service_Boundaries/FeatureServer

River courses, lake outlines, and selected mountain/desert region outlines: Natural Earth 1:10m public-domain vector data. Generalized for learning. Geographic regions are approximate; no sharp ecological boundary is implied. River flow speed, width, and animated arrows are enlarged for clarity. Lake polygons show shorelines; no bathymetry is modeled.
https://www.naturalearthdata.com/about/terms-of-use/

Park close-up color textures use the higher-resolution July 2004 NASA A1/B1 source imagery, decoded at half native size and reprojected onto each local elevation grid. Water pixels are recolored blue for legibility.