<p><i>Weaving a National Map</i> draws on contributions to a September 2002 workshop and the U.S. Geological Survey's (USGS) "vision" document for <i>The National Map</i>, envisioned by the USGS as a database providing "public domain core geographic data about the United States and its territories that other agencies can extend, enhance, and reference as they concentrate on maintaining other data that are unique to their needs." The demand for up-to-date information in real time for public welfare and safety informs this need to update an aging paper map series that is, on average, 23 years old. The NRC report describes how <i>The National Map</i> initiative would gain from improved definition so that the unprecedented number of partners needed for success will become energized to participate. The challenges faced by USGS in implementing <i>The National Map</i> are more organizational than technical. To succeed, the USGS will need to continue to learn from challenges encountered in its ongoing pilot studies as well as from other federal-led programs that have partnered with multiple sectors.</p>