Real USA: the whole country. Data used to build rusa_nature.bin (tools/usa/nature.py):

- Land cover: (c) ESA WorldCover project 2021 / Contains modified Copernicus Sentinel data (2021)
  processed by ESA WorldCover consortium. License: CC BY 4.0,
  https://creativecommons.org/licenses/by/4.0/. Changes: the 10 m map was read at its smallest
  internal overview (about 600 m, the most common class of each block), resampled to blocks of
  8 x 8 tiles at 80 m a tile in the EPSG:5070 Conus Albers projection, and turned into nature
  classes together with the state and the height.
- Elevation: AWS Terrain Tiles (terrarium, zoom 7), made from USGS 3DEP and other public sources.
- Borders: Natural Earth 10m admin-1 states and provinces (public domain).

Data used for the map cells, the vehicle zones and the world map (tools/usa/roads.py and the
files it runs):

- Roads, towns, rivers and the national border: Natural Earth 10m roads, populated places,
  rivers and lake centerlines, and admin-0 land boundary lines (public domain).
- Military installations: Military Installations, Ranges, and Training Areas (MIRTA), U.S.
  Department of Defense, Defense Installation Spatial Data Infrastructure (DISDI) Program
  (public domain), as archived in the HIFLD Archive: SeerAI, Inc. (2025), HIFLD Archive,
  https://source.coop/seerai/hifld, licensed CC BY 4.0,
  https://creativecommons.org/licenses/by/4.0/. Changes: sites grouped into installations,
  Army post names updated to their 2025 names, a few placed on the 1:80 map as fenced bases.
- Military land outlines: 1:1,000,000-Scale Federal Lands of the United States, National Atlas
  of the United States and U.S. Geological Survey, 2014 (public domain).
- Hospitals: HIFLD Open Hospitals, Oak Ridge National Laboratory and U.S. Department of Homeland
  Security, Geospatial Management Office (public use), as archived in the HIFLD Archive: SeerAI,
  Inc. (2025), https://source.coop/seerai/hifld, licensed CC BY 4.0,
  https://creativecommons.org/licenses/by/4.0/. Changes: open hospitals with 500 or more beds in
  the lower 48, merged per town; a few drawn as one building each.
- Fuel stations and arcades: Overture Maps Foundation, overturemaps.org, places release
  2026-09-23.1. Sources: Meta, Microsoft, PinMeTo, Krick, RenderSEO, DAC and BrightQuery under
  CDLA Permissive 2.0 (https://cdla.dev/permissive-2-0/); Foursquare under Apache 2.0
  (https://www.apache.org/licenses/LICENSE-2.0, notice:
  https://opensource.foursquare.com/places-notice-txt/), transformed to the Overture schema;
  AllThePlaces under CC0 1.0. Changes: stations grouped into highway fuel stops and thinned.
- San Antonio's River Walk (the town canal, tools/usa/cities.py): (c) OpenStreetMap contributors,
  available under the Open Database License (ODbL) 1.0, https://www.openstreetmap.org/copyright.
  Ways 225188887, 31733458, 229842442 and 31732684 (the San Antonio River), 51334205, 51334214,
  1289437139 and 51334216 (the horseshoe bend and its arms) and 92060042 (the Alamo Church's
  outline), saved in country/osm/. Changes: the ways joined end to end and laid at 0.45 squares a
  metre round our Alamo as a town canal with its banks and quays.

Data used to build rusa_climate.bin and the mod's RUSA_WeatherData.lua (tools/usa/climate.py):

- Climate: NOAA National Centers for Environmental Information, U.S. Climate Normals 1991-2020
  (monthly and hourly station normals), interpolated and rescaled for the game by Real USA.
  Modified data; not endorsed by NOAA. From the NOAA Open Data Dissemination bucket
  noaa-normals-pds. Changes: station values moved to each game cell's height and averaged over
  the nearest stations, then turned into differences from Elizabethtown, Kentucky (day high,
  night low) and ratios to it (wet days, rain per wet day, relative humidity).

Data used for the regions of the nature patterns (tools/usa/ecoregions.py, country/ecoregions_l3.bin;
docs/NATURE.md):

- Ecoregions: US Environmental Protection Agency, 2013, Level III Ecoregions of the Conterminous
  United States, U.S. EPA Office of Research and Development (ORD), National Health and
  Environmental Effects Research Laboratory (NHEERL), Corvallis, OR (public domain), from
  https://www.epa.gov/eco-research/level-iii-and-iv-ecoregions-continental-united-states. With
  thanks to the US EPA for the ecoregion framework (Omernik and Griffith 2014, Environmental
  Management 54(6): 1249-1266). Changes: the polygons filled onto the map's grid of 8 x 8 tiles
  (320 m) in the same EPSG:5070 Conus Albers projection.