Free GIS Data Sources¶
No more "Where do I get the data?" Below is the catalog I wish I'd had on day one. Most of these are free and authoritative (the agencies that actually produce the data).
Boundaries (administrative, political)¶
United States¶
| Dataset | Source | Notes |
|---|---|---|
| Census TIGER/Line (states, counties, tracts, places, etc.) | census.gov/tiger | Updated yearly; most-used US boundaries |
| Cartographic Boundary Files (lighter / more-generalized) | census.gov/CB | Easier to work with at small scales |
| US states / counties geojson | eric.clst.org/tech/usgeojson | Quick GeoJSON downloads |
Global¶
| Dataset | Source | Notes |
|---|---|---|
| GADM | gadm.org | Country admin levels worldwide |
| Natural Earth | naturalearthdata.com | Small-scale public-domain data |
| OpenStreetMap | openstreetmap.org | Detailed boundaries (via Geofabrik) |
Demographics & socioeconomic¶
| Dataset | Source | Notes |
|---|---|---|
| US Census / ACS | data.census.gov | Population, income, race, education, etc. |
| Census API | api.census.gov | Programmatic ACS access |
| CDC Social Vulnerability Index | atsdr.cdc.gov/svi | Tract-level vulnerability |
| HUD AFFH-T | hud.gov | Housing equity data |
| WorldPop | worldpop.org | Global gridded population |
| GHS-POP | ghsl.jrc.ec.europa.eu | European-Commission global pop grid |
| Eurostat | ec.europa.eu/eurostat | Europe demographics |
→ Detailed Census walkthrough: Census Data.
Roads, transit, transportation¶
| Dataset | Source | Notes |
|---|---|---|
| OSM roads (worldwide) | Geofabrik | Country-level extracts |
| US roads (TIGER) | census.gov/tiger | Yearly |
| GTFS (transit) | transit.land | 1000+ agencies |
| GTFS Schedule (Mobility Database) | database.mobilitydata.org | Open registry |
| OpenStreetMap public transport | openstreetmap.org | Includes bus stops, lines |
| FAA airports | faa.gov | US airports |
| OpenFlights | openflights.org/data | Global airports |
Land cover, land use¶
| Dataset | Source | Notes |
|---|---|---|
| NLCD (US, 30 m) | mrlc.gov | National Land Cover Database |
| ESA WorldCover (10 m, global) | esa-worldcover.org | 11-class global land cover |
| ESRI 10 m Land Cover | livingatlas.arcgis.com/landcover | Annual global product |
| Dynamic World (Google) | dynamicworld.app | Near-real-time global LC |
| USDA Cropland Data Layer | nassgeodata.gmu.edu/CropScape | US crop type, yearly |
Imagery (satellite & aerial)¶
| Dataset | Source | Notes |
|---|---|---|
| Landsat (30 m, since 1972) | USGS EarthExplorer | Free; Collection 2 |
| Sentinel-2 (10 m) | Copernicus Browser | EU; no signup needed |
| MODIS | USGS EarthData | Daily global, 250–1000 m |
| US NAIP (high-res aerial) | USDA NAIP | 1 m, leaf-on |
| Planet (limited free tier) | planet.com/education | Researchers / educators |
| ArcGIS Imagery Services | livingatlas.arcgis.com | Streamed imagery layers |
Elevation¶
| Dataset | Source | Notes |
|---|---|---|
| USGS 3DEP (DEM, ⅓ arc-sec ~10 m) | apps.nationalmap.gov | Best US elevation |
| Copernicus DEM (30 m, 90 m global) | Copernicus Browser | Best global DEM |
| SRTM (30 m, 90 m) | USGS | Older but ubiquitous |
| ASTER GDEM | NASA | Global, 30 m |
Hydrography & water¶
| Dataset | Source | Notes |
|---|---|---|
| NHD (National Hydrography Dataset) | USGS NHD | US streams, water bodies |
| WBD (Watershed Boundary Dataset) | USGS | HUC watersheds |
| HydroSHEDS | hydrosheds.org | Global river / watershed |
| OpenStreetMap water | openstreetmap.org | Decent water polygons |
Hazards & climate¶
| Dataset | Source | Notes |
|---|---|---|
| FEMA NFHL (flood zones) | msc.fema.gov | US flood maps |
| FEMA National Risk Index (NRI) | hazards.fema.gov/nri | 18 hazards by tract / county |
| NOAA Climate Data Online | ncei.noaa.gov/cdo-web | Weather station data |
| NOAA Storm Events | ncdc.noaa.gov/stormevents | Tornadoes, severe weather |
| US Wildfire | USDA WUI | Wildland-urban interface |
| Living Atlas Climate | livingatlas.arcgis.com | Many ready layers |
Buildings & footprints¶
| Dataset | Source | Notes |
|---|---|---|
| Microsoft Building Footprints | github.com/microsoft/USBuildingFootprints | 130M+ US buildings |
| Microsoft Global Building Footprints | github.com/microsoft/GlobalMLBuildingFootprints | Worldwide |
| Google Open Buildings | sites.research.google/open-buildings | Africa, Asia, Latin Am. |
| OSM Buildings | openstreetmap.org | Where mapped |
Health & equity¶
| Dataset | Source | Notes |
|---|---|---|
| CDC PLACES | cdc.gov/places | Census-tract health estimates |
| Area Deprivation Index | neighborhoodatlas.medicine.wisc.edu | US ADI |
| HRSA HPSA (health professional shortage areas) | data.hrsa.gov | Underserved areas |
| USDA Food Access Atlas | ers.usda.gov | Food access |
→ Walkthrough: Food Desert Project.
Open data portals to bookmark¶
- data.gov — US federal data portal.
- opendata.arcgis.com — ArcGIS Hub portals worldwide.
- usafacts.org — friendly demographic data.
- data.world — community datasets.
- GeoDA Data — sample datasets for spatial analysis.
- Your city, county, and state open data portals — search "[your city] open data."
Pro tips¶
Always read the metadata
Every dataset has metadata (or should). Read at least:
- Date / vintage — is it 5 years out of date?
- CRS — is it WGS84? State Plane? Web Mercator?
- Units — feet or meters? Miles or kilometers?
- Methodology — how was it collected, modeled, or estimated?
Beware the 'free download' that isn't
Some sources require an account, attribution, or even a license fee for commercial use. Check the license before publishing or selling derivatives.
→ Next: ArcGIS Documentation.