USGS maps have been downloaded by the millions since converting to digital delivery.
The U.S. Geological Survey, through the National Geospatial Program, has delivered more than 18 million US Topoquadrangles and Historic Topographic Maps in the past six years. A download is counted when a user select the desired map(s) from the USGS Storeor The National Map Viewer and places that file on their computer or mobile device for further manipulation.
In late 2009, the USGS began releasing a new generation of topographic maps, called the US Topomap, in electronic form. In 2012, the NGP complemented the new maps with the introduction and availability of high-resolution scans featuring more than 178,000 historical topographic maps of the United States, known as the Historical Topographic Map Collection (HTMC). Both of these digital products are accessible free of charge from their respective websites.
New Maps, New Content
The term “US Topo map” refers specifically to quadrangle topographic maps published since 2009. These maps are modeled on the familiar 7.5-minute quadrangle maps of the period 1947-1992, but are mass-produced from national GIS databases on a repeating, three-year cycle.
The first three-year production cycle for the conterminous 48 states was completed on schedule in September 2012. The second cycle will be completed in September 2015. Hawaii, Puerto Rico, and US Virgin Islands also have US Topo map coverage. Alaska has been started, but due to its size and technical challenges, is planned to be complete by 2018.
Legacy Maps Not Lost
The HTMC is an expansive database of high-resolution digital scans of legacy paper USGS map, some dating back to the agency’s inception in 1884. The HTMC map scans are “rectified” so they can be compared to each other and the newer US Topo maps. The NGP continues to partner with the USGS Library System in adding more historical topographic maps to the HTMC. The scope of the HTMC is 1 1:250,000 scale and larger published USGS topographic maps.
The most viewed and downloaded US Topo map is the Washington West, DC quadrangle, having been downloaded 2,785 times. The most popular HTMC map is the Half Dome, CA quadrangle, which has been downloaded a whopping 4,257 times.
On average nearly 280,000 US Topo and HTMC maps are downloaded each month. Meaning more than 9,300 downloads per day or nearly 400 every hour. The majority of downloads, approximately 66% are downloaded to .net or .com domains.
The US Topo and HTMC are products of The National Map (TNM).TNM is a collection of national geospatial databases (elevation, hydrography, geographic names, orthoimagery, land cover, transportation, boundaries, and structures) and associated products and services. The US Topo map is and example of a product derived from these databases—a digital topographic quadrangle map with fixed scale, traditional layout, and familiar design.
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