The National Map Corps consists of volunteers who devote some of their time to provide cartographic information to the U.S. Geological Survey. The only requirements to participate are having access to the Internet and a current familiarity with the area being mapped. This data is used to update The National Map.
The program originally allowed volunteers to collect geographic coordinates (latitude and longitude) via GPS receivers. The data was entered in spreadsheet format or in ESRI shapefiles and submitted via e-mail to the USGS National Geospatial Technical Operations Center(s) in Denver, Colorado, and Rolla, Missouri. During the registration process, prospective volunteers submitted a list of the 7.5 minute quadrangle maps on which they wished to work. Once accepted into the project, volunteers received their assignment and 1:24,000 scale topographic map of their quad. While there was no deadline for completing maps, the project's administrators preferred volunteers to submit coordinates for all structures in the quad no more than one year after beginning work.
In December 2006, a new Internet-based method for submitting information on structures was introduced. Using a web browser, volunteers are able to navigate maps and aerial photography, placing a point on the map and subsequently entering the name and type of structure.
From August 2008, the program stopped accepting structure data collected via GPS, but continued to use the web-based collection site.
Types of structures mapped
The following is a list of structures that can be entered on the web site. The focus is significant man-made structures. The "other" category is for man-made structures not on this list and should not include locations such as homes, restaurants or other commercial establishments.
- "The National Map Corp". U.S. Geological Survey.
- "Letter to volunteers describing changes in procedure" (PDF). U.S. Geological Survey. July 1, 2008. Archived from the original (PDF) on August 13, 2009.
- "Web-Based Volunteer Activity Lesson Plan (38 kB pdf file)" (PDF). U.S. Geological Survey. Archived from the original (PDF) on 2009-08-13.