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The Great Mapping Debate


I wanted to call attention to one of Administrator Fugate's recent posts on Twitter.

For those who might not know, the U.S. National Grid (USNG) is a standard that provides a nationally consistent language of location.  It breaks the United States into a series of grids, which can be used to reference an exact location on a map.

For many years, the USNG has been taught and used by the military, known as the Military Grid Reference System (MGRS), and used as the preferred way to reference location and navigate from point A to point B.  MGRS is taught and used on every operational level, from teaching entry level privates in basic training to helping senior staffs make strategic decisions.

The geo-locating system currently used by many emergency managers and first responders consists of latitude and longitude coordinates provided by global positioning systems (GPS) or given through a very tedious and time consuming manual method. 

While GPS devices are becoming more inexpensive and ubiquitous, the question remains, “What if GPS satellites or devices are rendered useless during an emergency?”

At FEMA, we're encouraging the adoption of the USNG for several reasons:

  • It's simple to implement and easy to use.
  • It provides interoperability, or a "common language", by making available a grid reference system that is seamless across jurisdictional boundaries. 
  • It provides scalability. Whether you have access to sophisticated geospatial software or are simply using a paper map, USNG can be used to pinpoint locations and make better operational decisions.
  • GPS devices complement USNG.  Most GPS receivers can translate GPS coordinates into the USNG grid.

As an example of USNG's use, FEMA's Urban Search and Rescue Response teams use it for positioning during search and rescue operations.  It is just one component of a geo-referencing matrix that is used for planning, coordination and information sharing purposes.  In fact, FEMA and other emergency support  agencies involved in supporting search and rescue (SAR) operations during a disaster, collaborated on the development of the United States National Search and Rescue Committee Catastrophic Incident Search and Rescue (CISAR) Addendum (PDF).  This Addendum establishes guidelines and standards for how position information will be communicated.

This is a critical issue for effective SAR coordination and responder safety.  During response operations, many search and rescue teams from various local, state, and federal agencies must coordinate their efforts.  By employing a standard system and adhering to the CISAR Addendum, which includes use of the USNG, teams are more equipped and prepared to communicate essential information in extreme circumstances.

As Administrator Fugate pointed out on Twitter, check out these two links to learn more.

  1. Federal Geographic Data Committee on USNG resources
  2. Fact sheet on USNG (PDF)

What are your thoughts on using the USNG standard versus GPS or latitude/longitude?  Feel free to leave your questions and feedback - we will try to address comments in future blog posts.

Last Updated: 
07/10/2012 - 16:15


The question is not for debate. We need to use USNG period and drop Lat/Long for ground use. The NSARC document and what happened at Katrina, makes that clear. USNG can be truncated, when users understand the rules for that and is easier to say and copy over a radio. It is simple x-y, easier to teach & understand, especially to those unfamiliar with any system. Three(3) versions of Lat/Long allow for error as happened with the Trooper 2 MD helicopter search. USNG needs leadership. We need a statement similar to the following: "All local, state, and federal governments, jurisdictions, departments, organizations, etc. SHALL implement and use US National Grid as soon as possible". As with DoD directives, air support to the ground shall use the ground operators coordinate system (MGRS/USNG), do not make the ground operator have to switch and potentially make an error. Once that is done...all users are literally on the same page. All maps in the convenience store, office supply store, etc. need to USNG. E911 location data for cell phones needs to be displayed as the nearest 100 meter grid (example: 14S QH 121 530). Add USNG to street addresses. USNG is interoperability.

All emergency services should be using USNG FOR GPS applications not as opposed to. <br />Those of us in Search and Rescue have used UTM / MGRS for many years and can easily convert to USNG.

Might USNG resources be made available for US Domestic Corporation Networks to resource "free of charge," that is as a thank you privilege for choosing to incorporate in the US?

David, in Florida, resources already offered but a little hard to find. If you hit the Florida DEM page, EM community page, bottom, there are resources for shp file of USNG, the gator map, etc. What we need to petition for is the internet map gurus, mapquest, google to offer a USNG layer.<br /><br />Oh and we all should add out USNG loc to our signatures. <br />USNG 17R NL 56120 60846

A nice blog entry re. USNG. Thanks, Mr. Fenton and thanks too for Dep. Admin Carwile and Administrator Fugate and their leadership and vision.

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The USNG also has the potential for raster type data display. When the USNG polygon shapefile is brought into ArcGIS it can be exported out in WGS84. You can then add point data locations to the map overlaying the USNG and find the number of point locations per grid square. When the number of points per grid square is added to the polygon as an attribute this can now be symbolized as a chloropleth map. The USNG polygon squares will become a "vector raster" with the ability delineate events 1000M X 1000M basis. This ability would be ideal for disease outbreak surveillance and responding to specific grid locations.

We need a statement similar to the following: "All local, state, and federal governments, jurisdictions, departments, organizations, etc. SHALL implement and use US National Grid as soon as possible".

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