Common Questions

After hurricanes in 2005, a need to support emergency response teams in search and rescue missions was identified. Accurate grids that could be tailored to a specific area of interest and scale were needed along with tools to provide efficient and precise identification of coordinates for a specific location. U.S. National Grid Tools for ArcGIS will provide those working in the field with the tools needed to perform these tasks.

U.S. National Grid Tools for ArcGIS is available as a free download for ArcGIS 9.1, 9.2, or 9.3.

The U.S. National Grid (USNG) system is based on and interoperable with the Military Grid Reference System (MGRS). The main difference is the 100,000-meter grid two-letter identification. The USNG lettering scheme is identical to the MGRS 100,000-meter grid lettering scheme for the North American Datum (NAD83). USNG, however, uses the same 100,000-meter lettering scheme for both NAD83 and NAD27, whereas MGRS has two lettering schemes for quick identification between the datums. USNG coordinates indicate that the coordinates are in the NAD27 datum by appending "(NAD27)" to the end of the coordinate, for example:

• The Washington Monument (USNG):
  18S UJ 2348 0647 [NAD83 is implied]
  18S UJ 2345 0626 (NAD27)

For more information on the U.S. National Grid, please visit Introducing the United States National Grid or www.fgdc.gov/usng.

At this release of the U.S. National Grid Tools for ArcGIS, USNG coordinates are supported only for the NAD83 and WGS84 datums.

The U.S. National Grid Tools for ArcGIS utilizes functionality provided by ArcGIS Military Analyst and the Production Line Tool Set (PLTS) Grid Manager. The missing icon on the toolbar indicates that one (or both) of these components has been uninstalled. To fix the problem, rerun the U.S. National Grid Tools for ArcGIS installer. Any missing components will be reinstalled, and the icon should no longer show as missing on the toolbar.

When identifying USNG coordinates with the Coordinate tool, the MGRS entry with the WGS84 datum selected should be used.

U.S. National Grid Tools for ArcGIS is an extension. In ArcMap, select the Tool menu and click Extensions. Check the U.S. National Grid Tools check box, then click the Close button.

At this release of U.S. National Grid Tools for ArcGIS, USNG coordinates are supported only for the NAD83 and WGS84 datums. When identifying USNG coordinates with the Coordinate tool, the MGRS entry with the WGS84 datum selected should be used.

U.S. National Grid Tools for ArcGIS capabilities are included in ArcGIS for Desktop 10. There is no separate add-on or download needed for releases of ArcGIS for Desktop 10 and higher. You can find more information about these tools on the following ArcGIS Resource Center pages:

• Adding a Military Grid Reference System (MGRS) or a U.S. National Grid
• Modifying MGRS or U.S. National overlay grids
• An overview of the Grids and Graticules toolset
• Using the Go To XY tool