In the North Carolina Maps project, the metadata for each map includes the bounding coordinates for the area shown by the map. This includes the latitude and longitude of the farthest points north, south, east, and west. Latitude and Longitude are given in decimal degrees (rather than the more familiar degrees / minutes / seconds format). In order to convert from degrees/minutes/seconds into decimal degrees, there is a helpful online tool at http://www.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html.
Why Record Bounding Coordinates?
Simply listing the states or counties shown on a map can give an imprecise picture of what is actually shown since borders and place names have changed over time. Bounding coordinates provide a stable, numerical way to express the area shown on a map. By capturing this data, it will be possible in the future to search for the items presented in North Carolina Maps using a geographic-based search system, such as the Geography Network Explorer developed by ESRI (For a statewide example of this, see the Kentucky Geographic Network) or the NGDA Globetrotter used by the Alexandria Digital Library. One of the best examples available now is at the University of Nevada at Las Vegas: http://digital.library.unlv.edu/isis/.
Tips and Tools for Determining Bounding Coordinates
Google Earth has been the most helpful tool for determining bounding coordinates for a specific area, though other online map applications are also beginning to show coordinates in their displays. The Finding Coordinates page in this guide is an extensive, step-by-step demonstration on locating bounding coordinates for historic maps using Google Earth.
While North Carolina's borders have changed over time, they have been fairly consistent for most of the last century. The last new counties (Avery and Hoke) were added in 1911. Small adjustments in county borders have been made since then (and continue to be the subjects of lawsuits and legislation to the present day) but these have usually been minor changes that are not reflected on any but the most detailed local maps.
To determine the bounding coordinates of many 20th-century county maps, the chart listing Bounding Coordinates for North Carolina Counties is a helpful reference. However, this chart represents only the current county boundaries, and should be used in conjunction with David Corbitt's excellent book, The Formation of the the North Carolina Counties, 1663-1943 (Raleigh: State Department of Archives and History, 1950). The default bounding coordinates for the modern state of North Carolina are as follows:
- MARC 255 - Cartographic Mathematical Data
- Dublin Core Coverage Element
- MODS User Guide: <subject><cartographics>