National Atlas of the United States Just Clicks Away

With a mandate from the federal government to produce a national atlas that makes use of current IT innovations, the United States Geological Survey (USGS) lost no time in deciding that an online digital edition would best serve the American public.

"One of the primary strengths in using a Web-based mapping system is the opportunity to use the technology to provide a window into additional information," comments Jay Donnelly, managing editor of the National Atlas.

With the active cooperation of more than 20 federal government agencies, including the U.S. Forest Service, the U.S. Bureau of the Census, and the Environmental Protection Agency, the USGS has produced an atlas utilizing the extensive databases of these and many other longtime GIS installations.

While the intent of the atlas is to characterize the patterns, trends, and conditions in the United States at the national level, regional information is seamlessly available by using the geographic names query or quadrangle grid function.

Currently, there are almost 150 individual map layers available from the National Atlas and this number is expected to double within the next six months. The USGS and its federal partners plan to supplement the National Atlas program with additional information on the World Wide Web. This information would explain more about the particular map theme the user has displayed and point him or her to appropriate sources of reliable supplemental information, if needed.

For example, a user could point with the cursor to hydrologic features on the displayed map and the system will return information about the features queried. Additionally, embedded within the displayed map information would be links that could take the user to other Web sites. The links might lead to site-specific information from EPA's Surf Your Watershed site to an engineering profile from the U.S. Army Corps of Engineers' dam inventory or to real-time streamflow data from the USGS.

Quality control is an important issue for the National Atlas production team and as Donnelly puts it, "We work very hard to integrate these data so that when people choose to download the information, what they're getting is the most accurate, authoritative, and reliable information that we can produce."

These data are fully documented and are available at no cost. More than 130,000 map layers (260 gigabytes of data) have been downloaded to date.

The system was originally built on Esri's MapObjects Internet Map Server (IMS) platform, but with the release of ArcIMS, the National Atlas team is currently implementing ArcIMS for Internet map publishing and ArcSDE for data management.

The site, www.nationalatlas.gov, has been up for more than two years. Volume is heavy with approximately 2.4 million requests for this free service each month.

The National Atlas provides online, interactive mapping that allows users to select or deselect map layers of interest to them. A popup legend can be displayed for symbology purposes. The maps that are created can be printed and there is a locator diagram available that indicates the location in America of the current map display.

"What we are attempting to do is make geographic information more accessible, meaningful, and useful to the American public. This is a different focus for us since our work is normally done on behalf of other researchers, government agencies, or land managers," continues Donnelly.

In addition to the more traditional mapping services, the National Atlas supports wildlife monitoring programs that provide indicators of the relative health of an ecosystem. Using multimedia techniques, the presentations are particularly engaging.

The animated exotic species map highlights the spread of the zebra mussel during the past 12 years from Lake St. Clair in the Great Lakes region down through the major rivers in the Midwest to Louisiana and the Gulf of Mexico. This freshwater mussel is native to the Balkans region of Poland. The species reproduces quickly and colonizes water intake pipes, severely limiting their flow. They cause billions of dollars of damage to municipal water systems and have no natural enemies in the United States. In addition, they threaten the food supply of other species. The supplemental photographs of clams and crayfish encrusted with zebra mussels are quite graphic.

"What we hope to establish with www.nationalatlas.gov is a central Web site for people to go to when they have a question about America that has a 'where' component to it. That is why I think it is so important for us to include demographic, economic, crime rate, climate, and public health information in the atlas. These are backyard interests, the things that affect people's daily lives," concludes Donnelly.

For more information, please contact Jay Donnelly at jpdonnelly@usgs.gov.

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