Frequently Asked Questions

Mapping, Remote Sensing, and Geospatial Data

The USGS provides the mapping and digital geospatial foundation for the Nation.

Filter Total Items: 203
Example of the Landsat 8 Aquatic Reflectance Science Product
Some Landsat products include Quality Assessment (QA) bands with unsigned integers that represent bit-packed information for each pixel. Details for individual products are at:  Landsat Level-1 (Collection 1 and Collection2)  Landsat Level-2 Surface Reflectance    Landsat Level-2 Provisional Aquatic Reflectance   These files must be unpacked to a...
Front page of USGS topographic maps symbol sheet
Like topographic maps, topographic map symbols have evolved over time. There is no single document that describes all the symbols used on all USGS topographic maps.   Topographic Map Symbols – Covers symbols on maps published 1947-2009. Most of these symbols are still in use. US Topo maps published 2013-present (PDF format only) have a topographic...
Image of 1:50,000 scale NGA Christmas, AZ topo map
The USGS has a limited number of 1:50,000-scale maps available for the United States. These are maps that the National Geospatial Agency (NGA) has released for sale to the public.   To see which maps are available for sale (or free digital download), go to the online USGS Store:  Click on “Maps” in the left navigation menu. Look for the NGA...
Landsat Collection 2 Generation Timeline
Landsat Level-2 Surface Reflectance and Surface Temperature products require Landsat Collection 2 Level-1 scenes that have been processed to Tier 1 or Tier 2, as well as additional auxiliary data. For Landsat 7, the timeframe from acquisition (Real-Time (RT)) to Tier 1 or Tier 2 takes approximately 25-27 days. For Landsat 8 scenes, the timeframe...
National Map Viewer with draw tool open
Base map data layers in The National Map Viewer are for viewing only. This application is designed for visualizing data, combining different data layers, and creating (and printing) your own maps. To download data from The National Map, see the link at the top of the Viewer for the Data Download Client.  None of the base map layers are available...
Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010)
Download global elevation data products using EarthExplorer or AppEEARS. In EarthExplorer, select “Digital Elevation” under the "Data Sets" tab and choose an option:  ·     Shuttle Radar Topography Mission (SRTM) 1-arc-second (30m) resolution DTED, BIL, and GeoTIFF formats Acquired 2000 ·     Global Multi-resolution Terrain Elevation Data 2010 (...
Color map of land use and land cover in West Africa, circa 1975
Access global land cover data using two sources on EarthExplorer: Global Land Cover Characterization (GLCC)  Select "Land Cover" under the "Data Sets" tab in EarthExplorer. Select area of coverage and projection under "Additional Criteria" tab. Derived from 1-km Advanced Very High Resolution Radiometer (AVHRR) data collected April 1992-March 1993...
Screenshot from NHD Seminar 6 Presentation showing Terrain Catchments
The USGS does not require a specific format when citing our datasets, but a few suggestions and examples are below. Citation for Datasets Author: U.S. Geological Survey Release date: the first four numbers of <pubdate> from dataset metadata for the year of the release date. For example, if the <pubdate> is 20190426, the year 2019...
3D Lidar Point Cloud Image of San Francisco Bay and Golden Gate Bridge
Status maps showing 3D Elevation Program (3DEP) product availability and recent updates are on the 3DEP Product Availability site. Areas containing recent updates are refreshed on a monthly basis. Download spatial metadata shapefiles showing the updated areas for each product from the 3DEP Product Metadata site. Acquire updated products through...
Lidar-derived Digital Elevation Model over Zion National Park, Utah
Digital elevation data are available through The National Map Download Client. Click the “How To” link at the top of the viewer for detailed instructions on how to find and download data. There is a seperate site for Services. The 3D Elevation Program (3DEP) products and services available through The National Map consist of standard digital...
1951 USGS legacy topographic map of the Monson West, ME
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. The best known USGS maps are the 1:24,000-scale topographic maps, also known as 7.5-minute quadrangles. Download all dates and scales of USGS topographic maps free of charge from the following applications or order paper copies of all...
Sentinel-2A satellite image showing the Crater Lake in Oregon.
The Sentinel-2A MultiSpectral Instrument (MSI) data has spectral bands very similar to Landsat 8 (excluding the thermal bands of Landsat 8’s Thermal Infrared Sensor). Source: https://landsat.gsfc.nasa.gov/wp-content/uploads/2015/06/Landsat.v.Sentinel-2.png (Public domain.)   Learn more: USGS EROS Sentinel-2 Landsat Comparison