Geographers are also involved in several other research initiatives that will contribute to the NSDI, including the following:

• The National Center for Geographic Information and Analysis leads research into the fundamental design and operations of GISs, as well as related efforts (e.g., the Alexandria Project) to develop methodologies and tools for the creation of a digital spatial ''library." This library will allow decision makers, researchers, and the general public to easily access georeferenced information through the Internet.
• The U.S. Environmental Protection Agency's (EPA) Environmental Monitoring and Assessment Program (EMAP) monitors ecosystem changes at various spatial scales. The hierarchical database structure developed for EMAP now serves as a basis for much of EPA's environmental monitoring and analysis activities.
• The USGS's National Digital Cartographic Database supports the production of paper and electronic maps (see Sidebar 6.7).
• The U.S. Bureau of the Census has developed the Topologically Integrated Geographical Encoding and Referencing (TIGER) database (see Chapter 4).
• The U.S. Department of Energy's Environmental Spatial Analysis Tool (ESAT) project evaluates waste management alternatives.
• The National Center for Health Statistics has developed a cancer atlas.
• The U.S. Department of Transportation's Bureau of Transportation Statistics has undertaken a project to compile, analyze, and distribute data about the nation's transportation system.