Methodology & data sources

Last updated 2026-10-26.

How elevation is found

Points in the United States

For locations in the 50 states, Washington, DC, Puerto Rico and the U.S. Virgin Islands we ask the USGS Elevation Point Query Service, which returns the ground elevation from the USGS 3D Elevation Program (3DEP). USGS reports an overall vertical accuracy (RMSE) of about 0.53 m (1.7 ft) for 3DEP.

Points outside the United States

Everywhere else, and for any U.S. point where USGS has no value, we read Terrain Tiles on AWS, an open elevation dataset built by Mapzen. We fetch the zoom-15 tile that contains the point (about 4.8 m per pixel at the equator), decode its elevation values, and interpolate between the four nearest pixels. The tiles blend several elevation models, so resolution and accuracy depend on the country: from a few meters where national lidar exists (for example the United Kingdom) to 30 m from SRTM or coarser in other places. Ocean points return depths from ETOPO1.

Each tile records which datasets it was built from, and each result lists only those credits under "Data sources". The full list is below.

Accuracy shown with each result

The "Accurate to about ±…" line uses the vertical accuracy the data publisher reports for the dataset behind that value (listed with each dataset below). When a value blends several datasets we show the largest figure. When a dataset has no published accuracy, we show no number rather than estimate one.

Units and rounding

Results are shown in feet first, with meters alongside (1 ft = 0.3048 m). The API returns values to 0.1; the result card rounds feet to the nearest whole foot. Elevation is for the ground at that point, not the height of your device above it. When you use your device location, the result also shows how accurately your device placed you.

Caching

Lookups are stored on our server for up to 90 days, so repeat requests for the same point return the same value.

Addresses, counties, ZIP areas and time zones

Address search (U.S. only):U.S. Census Bureau Geocoder. It matches street address ranges, so remote places without ranged addresses (for example inside Death Valley) may not match.
County, state and ZIP area (U.S. only): Census Geocoder geographies. The ZIP shown is the Census ZIP Code Tabulation Area (ZCTA), which approximates the USPS ZIP code area.
Street address from coordinates:OpenStreetMap Nominatim.
Time zone: a simplified copy of the timezone-boundary-builder boundaries. Points within a few hundred meters of a zone border can be assigned the neighbouring zone.
Map:USGS The National Map topographic basemap (U.S. coverage).

City, state, peak and capital pages

Place pages are generated from data files built by our pipeline (scripts/data/build.mjs); no figure is typed in by hand. Each page lists its own sources and the date the data was built.

Headline figures

US cities: the USGS 3DEP elevation at the city-center point (the USGS GNIS populated-place coordinates, or the Census internal point when the GNIS point lies outside the city boundary), labelled "USGS elevation downtown". An official elevation is shown beside it only when we cite it directly from its publisher, for example Denver's 5,280 ft step at the Colorado State Capitol.
Peaks: the published summit elevation, from the first available of: an official figure we cite directly; the NAVD 88 height of a NOAA National Geodetic Survey mark on the summit (ground marks within 0.25 mi of the highest grid value, no more than 15 ft below or 30 ft above it, measured heights before heights scaled from a map); the USGS Elevations and Distances table for state high points; a figure from a source cited on Wikidata. When none exists, the headline is the USGS grid value and says so.
States: the current high-point figure with its source and date (the same published figure as the peak page, or a cited official figure), otherwise the USGS Elevations and Distances table (revised 2001, NGVD 29). Low points come from that table.
World capitals: the Terrain Tiles elevation at the city's Wikidata coordinates.

Sampled values

Ranges and averages are labelled "sampled". For a US city we query USGS 3DEP at the center plus a regular grid of 60–250 points inside the 2024 Census boundary; for a state, 180–260 grid points inside the state; for a peak, points 50 m apart within 250 m of the GNIS summit; for a capital, points 750 m apart within 5 km of the center, leaving out points at sea. The true highest and lowest points can fall between grid points, and elevation grids average each cell, so they read a few feet to a few hundred feet low on sharp summits.

Quality rules

A page needs at least eight place-specific data points; thinner pages are marked noindex.
Where an official figure and the USGS value differ by more than 150 ft, the page explains why.
Ten percent of each batch is spot-checked against the USGS National Map and one independent source.

Data credits

USGS Elevation Point Query Service

3DEP data courtesy of the U.S. Geological Survey

Terrain Tiles on AWS

Terrain Tiles by Mapzen, hosted on AWS Open Data. Datasets in the tiles, their licenses and required credits:

SRTM (global, 30 m)
License: U.S. public domain
Published vertical accuracy: 16 m (52 ft) LE90
SRTM terrain data courtesy of the U.S. Geological Survey
GMTED2010 (global, 250 m)
License: U.S. public domain
Published vertical accuracy: 30 m (98 ft) RMSE
GMTED2010 terrain data courtesy of the U.S. Geological Survey
USGS 3DEP (United States)
License: U.S. public domain
Published vertical accuracy: 0.53 m (1.7 ft) RMSE
United States 3DEP (formerly NED) terrain data courtesy of the U.S. Geological Survey
ETOPO1 (global ocean bathymetry)
License: U.S. public domain
Published vertical accuracy: not published
Global ETOPO1 terrain data U.S. National Oceanic and Atmospheric Administration
NOAA Great Lakes bathymetry
License: U.S. public domain
Published vertical accuracy: not published
Great Lakes bathymetry courtesy of the U.S. National Oceanic and Atmospheric Administration (NCEI)
ArcticDEM (land north of 60°)
License: Unlicensed; may be used, distributed and modified without permission
Published vertical accuracy: not published
ArcticDEM terrain data DEM(s) were created from DigitalGlobe, Inc., imagery and funded under National Science Foundation awards 1043681, 1559691, and 1542736
Geoscience Australia 5 m DEM
License: CC BY 4.0
Published vertical accuracy: not published
Australia terrain data © Commonwealth of Australia (Geoscience Australia) 2017
Digitales Geländemodell Österreich (data.gv.at)
License: CC BY 3.0 AT
Published vertical accuracy: not published
Austria terrain data © offene Daten Österreichs – Digitales Geländemodell (DGM) Österreich
Canadian Digital Elevation Model (NRCan)
License: Open Government Licence – Canada
Published vertical accuracy: not published
Canada terrain data contains information licensed under the Open Government Licence – Canada
EU-DEM (Europe)
License: Copernicus free and open data
Published vertical accuracy: 2.9 m (9.5 ft) RMSE
Europe terrain data produced using Copernicus data and information funded by the European Union - EU-DEM layers
INEGI continental relief (Mexico)
License: INEGI free use of information
Published vertical accuracy: not published
Mexico terrain data source: INEGI, Continental relief, 2016
LINZ 8 m DEM (New Zealand)
License: CC BY 3.0 NZ
Published vertical accuracy: not published
New Zealand terrain data Copyright 2011 Crown copyright (c) Land Information New Zealand and the New Zealand Government (All rights reserved)
Kartverket digital terrain model (Norway)
License: CC BY 4.0
Published vertical accuracy: not published
Norway terrain data © Kartverket
Environment Agency LIDAR composite DTM (United Kingdom)
License: Open Government Licence v3
Published vertical accuracy: 0.15 m (0.49 ft) RMSE
United Kingdom terrain data © Environment Agency copyright and/or database right 2015. All rights reserved

Source of this list: Tilezen attribution guide.

Other sources

Address, county, state and ZIP area data: U.S. Census Bureau (public domain).
Map tiles: USGS The National Map.