An interesting update came our way via the USGS as more than 50% of the Nation is now "covered" by new USGS digital maps; either the US Topo or earlier released "Digital Map - Beta". The number of quads available for free download from the US Store is actually much more than half the contiguous US!
US Topo is the next generation of digital topographic maps from the U.S. Geological Survey. Arranged in the traditional 7.5-minute quadrangle format, digital US Topo maps are designed to look and feel like the traditional paper topographic maps for which the USGS is so well known. At the same time, US Topo maps provide modern technical advantages that support wider and faster public distribution and enable basic, on-screen geographic analysis for all users.
US Topo maps are available free on the Web. Each map quadrangle is constructed in GeoPDF® format from key layers of geographic data – orthoimagery, roads, geographic names, contours and hydrographic features - found in The National Map, which is a nationwide collection of integrated data from local, State, Federal, and other sources.
US Topo users can turn geographic data layers on and off as needed; zoom in and out to highlight specific features or see a broader context; and print the maps, in their entirety or in customized sections, on a wide variety of printing devices. Additional analytical tools are available free for download. File size for each digital 7.5-minute quadrangle is about 15-20 megabytes.
The prototype of US Topo, "Digital Map–Beta," has been available since June 2009 and currently covers 17 states. US Topo maps include all of the content of the earlier "Digital Map–Beta," plus integrated contours and hydrographic features.
As the US Topo product evolves, the USGS will provide digital versions of earlier edition topographic quadrangle maps and will incorporate additional geographic data layers from The National Map.
As of October 2009, the USGS began to load US Topo maps to the USGS Store distribution point where the maps will be available for free download. Existing "Digital Map–Beta," will continue to be available for free download. As available, they will be eventually replaced by revised and enhanced US Topos produced by the USGS National Geospatial Technical Operations Center.
What Makes the USGS US Topo Different from Other Electronic Maps?
Richer content, multiple layers of data, more than a street map
Can be used on the computer or printed to scale
Looks and feels like legacy paper USGS topographic maps but has technical advantages
Nationally consistent data quality assured to high standards
Downloadable free from the USGS Store
Free, downloadable user tools
Users can select from various reference systems: Latitude/Longitude, UTM (Universal Transverse Mercator), and MGRS (Military Grid Reference System)
Direct "mash-up" capabilities with Google Maps®
Continuous evolution and incorporation of additional data layers
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