The shoreline was created from data captured (digitized from scanned images of the master separates of the NOS Charts) from over 270 National Ocean Service Navigation Charts and spans some 80,000 nautical miles at an average map scale of 1:70,000.
The data set is designed for a broad target audience ranging from governmental agencies, universities and other research institutions, to the private sector, and students, as well as any other concern requiring a general purpose digital shoreline layer for GIS and cartographic projects.
Spatial data were derived directly from National Ocean Service Navigation Charts. The NOS Chart Products meet or exceed National Map Accuracy standards (hard copy); the digital data supplied in this compilation should, when plotted at scale, meet or exceed these same cartographic standards.
The previously digitized coastlines were combined to create a polygon representation of the 48 contiguous United States.
Although these data have been used by the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the U.S. Geological Survey as to the accuracy of the data.