Contours - 12 of 12
Contours FAQs - 12 Found
The USGS National Geospatial Program derives contours from the National Elevation Dataset (NED) 1/3 arc-second data for US Topo topographic map products. These contours are also distributed as GIS compatible vectors in 1x1 degree tiles through The National Map viewer. Contours on adjacent US Topo quadrangle maps usually match to within 1:24,000 scale accuracy standards, but exact joins in all cases are cost-prohibitive, and the map series does not require that contours join exactly. In addition, it is common for adjacent quadrangles to have different contour intervals. Users who need seamless data or use elevation data for analytic purposes, are encouraged to use the NED instead of derived contours. NED data can also be downloaded through The National Map viewer.