When significant changes in the landscape have occurred, contours will be updated on an as-needed basis.
The 100-foot contours were derived from 3DEP (formerly National Elevation Dataset) one arc-second resolution data that was sub-sampled to a cell size of three arc-second. The 50-foot contours were also derived from one arc-second data. Large-scale contours were derived from 1/3 arc-second resolution data for US Topo products.
The seamless digital elevation models (DEMs) used to create the contour lines are enhanced as we collect lidar over the US through the 3DEP program.
Learn more:
Related Content
Are depression contours identified in 3D Elevation Program (3DEP) contour products?
Yes, depression contours are identified with tick marks in 3D Elevation Program products, but only in large scale contours (1:36,000 scale to 1:18,000 scale).
What are the projection, horizontal and vertical datum, format, and distributed tile extent of 3D Elevation Program (3DEP) contours?
Contours are not projected, but are provided in geographic coordinates (latitude and longitude) in units of decimal degrees, and horizontally referenced to the North American Datum of 1983. Contour elevation values are vertically referenced to the North American Vertical Datum of 1988. Contours are staged in Esri File Geodatabase 10.1 or Shapefile format, and distributed in 1x1 degree tiles.
What geographic areas do 3D Elevation Program (3DEP) contours cover?
3D Elevation Program (3DEP) contours cover all of the United States and its territories at multiple scales: Small scales (1:578,000-1:289,000) Medium scales (1:144,000-1:72,000) Large scales (1:36,000-1:18,000) Contours are easily viewed in The National Map Viewer and USGS topographic maps, or downloaded through The National Map Download Client. Learn more: Map Scales
How do I report errors in 3D Elevation Program (3DEP) elevation data?
If you think you’ve found an error in USGS elevation data, please send an email to tnm_help@usgs.gov. We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors are of concern to us. We are working to correct or minimize known issues, but it will take some time. Errors...
Why don't the elevations on your maps agree with those provided by my GPS system? Which are correct?
Elevations provided by your GPS receiver might disagree with elevations on a USGS map, but they could both be correct if they reference different vertical and/or horizontal datums. The default horizontal datum setting on most GPS receivers is the World Geodetic System of 1984 (WGS84) and the elevations are based on the NAD83 ellipsoid. USGS topographic maps published after 2009 are georeferenced...
How accurate are elevations generated by the Elevation Point Query Service in The National Map?
The National Map’s Elevation Point Query Service (EPQS) returns elevations that are interpolated from the 3DEP dynamic elevation service. This is a web coverage service (WCS) that includes multiple resolutions of DEMs including 1 meter resolution lidar-based DEMs where available, and 1/3 arc-second seamless DEMs. The accuracy of the elevations returned by EPQS will vary according to the source...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. USGS topographic maps have been published at many scales, but 1:24,000 (also referred to as a 7.5-minute quadrangle) has been the standard topographic map scale since 1947. For Alaska the standard scale is 1:25,000. All dates and all scales of our topographic maps can be freely...
What types of elevation datasets are available, what formats do they come in, and where can I download them?
Digital elevation data for the United States and its territories are available through The National Map Downloader. Click the “Help” link at the top of the page for detailed instructions on how to find and download data. There is a separate site for The National Map Services. The 3D Elevation Program (3DEP) products and services available through The National Map consist of standard digital...
Related Content
- FAQ
Are depression contours identified in 3D Elevation Program (3DEP) contour products?
Yes, depression contours are identified with tick marks in 3D Elevation Program products, but only in large scale contours (1:36,000 scale to 1:18,000 scale).
What are the projection, horizontal and vertical datum, format, and distributed tile extent of 3D Elevation Program (3DEP) contours?
Contours are not projected, but are provided in geographic coordinates (latitude and longitude) in units of decimal degrees, and horizontally referenced to the North American Datum of 1983. Contour elevation values are vertically referenced to the North American Vertical Datum of 1988. Contours are staged in Esri File Geodatabase 10.1 or Shapefile format, and distributed in 1x1 degree tiles.
What geographic areas do 3D Elevation Program (3DEP) contours cover?
3D Elevation Program (3DEP) contours cover all of the United States and its territories at multiple scales: Small scales (1:578,000-1:289,000) Medium scales (1:144,000-1:72,000) Large scales (1:36,000-1:18,000) Contours are easily viewed in The National Map Viewer and USGS topographic maps, or downloaded through The National Map Download Client. Learn more: Map Scales
How do I report errors in 3D Elevation Program (3DEP) elevation data?
If you think you’ve found an error in USGS elevation data, please send an email to tnm_help@usgs.gov. We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors are of concern to us. We are working to correct or minimize known issues, but it will take some time. Errors...
Why don't the elevations on your maps agree with those provided by my GPS system? Which are correct?
Elevations provided by your GPS receiver might disagree with elevations on a USGS map, but they could both be correct if they reference different vertical and/or horizontal datums. The default horizontal datum setting on most GPS receivers is the World Geodetic System of 1984 (WGS84) and the elevations are based on the NAD83 ellipsoid. USGS topographic maps published after 2009 are georeferenced...
How accurate are elevations generated by the Elevation Point Query Service in The National Map?
The National Map’s Elevation Point Query Service (EPQS) returns elevations that are interpolated from the 3DEP dynamic elevation service. This is a web coverage service (WCS) that includes multiple resolutions of DEMs including 1 meter resolution lidar-based DEMs where available, and 1/3 arc-second seamless DEMs. The accuracy of the elevations returned by EPQS will vary according to the source...
How do I find, download, or order topographic maps?
The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. USGS topographic maps have been published at many scales, but 1:24,000 (also referred to as a 7.5-minute quadrangle) has been the standard topographic map scale since 1947. For Alaska the standard scale is 1:25,000. All dates and all scales of our topographic maps can be freely...
What types of elevation datasets are available, what formats do they come in, and where can I download them?
Digital elevation data for the United States and its territories are available through The National Map Downloader. Click the “Help” link at the top of the page for detailed instructions on how to find and download data. There is a separate site for The National Map Services. The 3D Elevation Program (3DEP) products and services available through The National Map consist of standard digital...
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