The points for the coverage were capture from the Resources Inventory Map series by on-screen digitizing. The eagle symbols were captured as points by following the shoreline of the river on the DLG's and operator visual interpretation of the source data. The points were extracted from the Resources Inventory for the Upper Mississippi River, 1984. A point is a 0-dimensional object that specifies geometric location. One coordinate pair specifies the location.
Points represent features like named places.
They have no length and are defined as a single x,y coordinate pair. Lines represent linear features like railroads. Polygons represent features like counties or lakes and are defined as a string of x,y coordinate pairs with the same beginning and ending points. These attributes are stored in Feature Attribute Tables. The feature attribute table contain information about and values for a particular record.