Slope represents the change of elevation over a specific area.
LF 2020 Update Slope Degree (SlpD) and Slope Percent Rise (SlpP) products (released February 2022) are generated from 1 arc-second Digital Elevation Models (DEM) tiles (approximately 30 meter) downloaded November 9, 2021 from The National Map (TNM) Viewer (v2.0), part of the USGS 3D Elevation Program (3DEP) which provides the best available public domain raster elevation data of the conterminous United States (CONUS), Alaska, Hawaii, and insular areas.
See metadata by extent for specific details regarding coordinate system and projection information.
Note: New with LF 2020, topographic products are consistently calculated from true north, a correction from earlier topographic products where Aspect was calculated incorrectly. Users are advised to download the new LF 2020 topographic products for CONUS, HI, AK, and PRVI to replace LF topographic products previously downloaded. We also advise that LCP files created from earlier topographic products be re-created using the new LF 2020 topographic products.
90 Kilometer Buffer: LF 2020 products include a 90-kilometer (km) buffer into neighboring countries. For CONUS, the buffer goes 90km into Mexico and Canada; for AK, the buffer goes 90km into Canada.