May 20, 2014
Recent wildland fires in San Diego County undeline the importance of having a universally understood grid system for first responders. A uniform coordinate system allows anyone to relay or find a location without significant local knowledge. Whether you are from Carlsbad or Cleaveland, you'll be able to find the spot using the US National Grid system. For example, many people in San Diego County may know where, say, Oak Grove is, but not many from outside the County could quickly find it on a map. However, if you are familiar with the US National Grid (USNG) you will easily be able to locate it at 11S NS 1927 9430.
The USNG is an alphanumeric point reference system that overlays the Universal Transverse Mercator (UTM) numerical coordinate system. A USNG coordinate consists of the Grid Zone Designation (GZD), 100,000-meter Square Identification; and Grid Coordinates. SanGIS is located at 11S NS 87878 32844 (approximately):
The beauty of the USNG is that it can be easily abbreviated in local areas to make it more easily communicated. All of San Diego County is in Grid Zone Designation 11S so that can be assumed when working in the area. Most of the County is covered by either the MS or NS Square Identifiers, so those can be assumed if the general area is known. This makes it much easier to communicate coordinates quickly when everyone already knows the general vicinity. It is only necessary to provide the grid coordinates instead of the full address.
There is a wealth of information on the USNG available from the Federal Geographic Data Committee (FGDC). To learn more about the USNG, how it was created, and how to use it visit the FGDS's USNG web site.
To facilitate use and implementation of the US National Grid, SanGIS has created two data layers and a layer package. The data layers provide the 10 km and 1 km grids in ESRI shape file format. The layer package includes the data along with color representations and scale dependent labels. The layer package can be easily dragged into an ESRI ArcMAP session. You can get the USNG grid layers and/or layer package from the SanGIS/SANDAG Regional Data Warehouse.