Methodology & data sources

Where the data comes from

• National Park Service API: park details, entrance fees and passes, operating hours, alerts, campgrounds, visitor centers, things to do, events, and news releases. This is the backbone of every park page.
• National Weather Service API: the live forecast on each park page loads in your browser directly from the NWS at view time, so it is always current.
• EPA AirNow: current air quality readings, loaded live in your browser. The data is owned and provided by federal, state, local, and tribal air quality agencies together with the EPA AirNow program.
• Recreation.gov (RIDB): campground reservability, booking links and site counts. The booking link is the Recreation.gov listing the Park Service itself links to; a campground without one is matched by name and location. Where the two sources give different site counts for a campground with its own Recreation.gov listing, the Recreation.gov count is shown, because that is the inventory people book against.
• NPSpecies: official Park Service species inventories behind each park's wildlife section.
• USGS stream gauges: live river flow readings, loaded in your browser from gauges near each park.
• USDA SNOTEL: snowpack depth at the nearest mountain telemetry station, refreshed daily.
• NOAA buoys: water temperature at the nearest offshore buoy for coastal parks, refreshed daily.
• NOAA Space Weather: aurora outlook for far-north parks, loaded live in your browser.
• NOAA tides: today's tide predictions for coastal parks, from the nearest station.
• USGS earthquakes: recent seismic activity within 50 km, loaded live in your browser.
• iNaturalist: the "seen this month" wildlife strip aggregates counts of research-grade community observations near each park, refreshed daily. Counts only; individual observations and photos remain on iNaturalist.
• Wikidata: establishment dates, land area, and UNESCO World Heritage status (public-domain structured data, CC0).
• Wikipedia and NPMaps: linked from park pages for further reading and printable maps. We link to these sources rather than republishing their content.
• Interactive maps are the National Park Service's own, embedded unmodified.

Open data

Our cleaned aggregate tables (parks, entrance fees, campgrounds, species counts) are published as CSV at github.com/kirkwood-justin/park-atlas-data, dedicated to the public domain under CC0. Each file carries the retrieval date of the underlying federal data. Corrections and questions: open an issue there.

How often it updates

Park Service data was last retrieved October 14, 2026. We refresh the full dataset on a regular schedule and rebuild affected pages; the footer of every data page carries the retrieval date. Alerts and reservation requirements change fast, so always check the official park page, linked at the top of every park page here, immediately before travel.

What we do to the data

We normalize designations, group parks by state and activity, convert records into readable tables, and clearly attribute any prose written by the Park Service itself. Where no structured data exists for a field, we say so rather than guessing.

Known limitations

• Roughly a quarter of park units publish structured fee data; the rest are free or publish fees only as prose.
• Operating hours describe standard schedules; weather closures may not appear until the Park Service posts an alert.
• Wikidata facts (established dates, area) are community-maintained and occasionally lag official records.
• Park photos are National Park Service images, credited as provided by the API.