Maps and Mapping

3D Elevation Program (3DEP) product updates and status maps are available at these sites: Updates The National Map Data Delivery News Subscribe to Simple Notification Services to receive emails regarding changes to the status of The National Map Services Status Maps The National Map Download Client – Click “Show” below each elevation product LidarExplorer – Lidar point cloud only DEM Availability...

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...

The U.S. Geological Survey (USGS) has been the primary civilian mapping agency of the United States since 1879. Some of the most well-known USGS maps are the 1:24,000-scale topographic maps, also called 7.5-minute  quadrangles . In 2009, the USGS transitioned from our hand scribed historical topographic maps to US Topos , which are computer-generated on a regular schedule using national databases...

Many different horizontal reference datums exist, but in the United States only three datums are commonly used: The North American Datum of 1927 ( NAD27 ) uses a starting point at a base station in Meades Ranch, Kansas and the Clarke Ellipsoid to calculate the shape of the Earth. The North American Datum of 1983 ( NAD83 ) was developed when satellites enabled a better model. Depending on one’s...

View map indexes on these interactive maps (you must zoom in to see the index lines and map names) : Map Locator on the USGS Store - Click the icon on the left that looks like two pieces of paper and select “1:24,000” for our standard map series. TopoView - Click on any of the round map scale indicators on the right side of the map. The National Map Viewer - Click on the Layer List icon at the top...

The distinctive characteristic of a  topographic map  is the use of elevation contour lines to show the shape of the Earth's surface. Elevation contours are imaginary lines connecting points having the same elevation on the surface of the land above or below a reference surface, which is usually mean sea level. Contours make it possible to show the height and shape of mountains, the depths of the...

Once you've gathered as many facts about family history and customs as possible, turn to maps to uncover more specific information or to solve historical mysteries. In the United States, birth, death, property, and some other kinds of records are normally kept by county governments. If you can name the place where an ancestor lived, new or old maps of that place might show the county seat where...

A diagram at the bottom of most USGS topographic maps shows three north arrows--true north, grid north, and magnetic north--and the angles between them. Some maps, especially very old maps, do not have this diagram. True north, also called geodetic north or geographic north, is the direction of the line of longitude that bisects the quadrangle. All longitude lines converge to points at the north...

A USGS topographic map is usually named for the most prominent feature within the bounds of the map, frequently a community. Most topographic maps are named for the most centrally located, well-known, and/or largest community labeled on the map. If the community for which the map should be named falls on two or more maps, a directional term might be used such as East and West. An example is...

Light Detection and Ranging ( lidar ) is a technology used to create high-resolution models of ground elevation with a vertical accuracy of 10 centimeters (4 inches). Lidar equipment, which includes a laser scanner, a Global Positioning System (GPS), and an Inertial Navigation System (INS), is typically mounted on a small aircraft. The laser scanner transmits brief pulses of light to the ground...

The U.S. Geological Survey (USGS) Earth Resources Observation and Science Center (EROS) can only certify that the product downloaded through our website is an authentic reproduction of an official record of the government that is in the legal custody of the USGS EROS Center . See the standard Authenticity of Digital Imagery document.

Yes, there is a plan to scan and digitize all rolls of film. The plan is to first scan all rolls of film that are in danger of decay from vinegar syndrome and then scan everything else. Science and customer requirements are also reviewed on a regular basis, but a formal, online schedule is not available. Learn more: USGS EROS products overview USGS EROS Aerial Photography Frequently Asked...