Frequently asked question
"A High Accuracy Reference Network (HARN) is a statewide or regional upgrade in the accuracy of NAD 1983 coordinates using Global Positioning System (GPS) observations." (National Geodetic Survey: Frequently Asked Questions)
In connection to a HARN upgrade, sometimes called a re-adjustment, grid files are available that can be used to convert from the original NAD 1983 (1986) coordinate system to the HARN. The grid files were published by the US National Geodetic Survey (NGS) for different states, or groups of states, at various times.
The below list of principal datum tags should reflect the publication dates of the HARN grid files.
Note: This information is copied from page 13 of the PDF document available in the Related Information section. The document, the Operator's Guide to the GEOCON software is from a beta webpage, so it is also attached. Be sure to check the NGS home page for the latest information on GEOCON software.
If more than one tag is listed for a state, there was a later upgrade. HARN grid files were not published for later upgrades.
LIST OF PRINCIPAL DATUM TAGS ----------------------------------------------------- AK Alaska NAD 1983 (1992) AL Alabama NAD 1983 (1992) AR Arkansas NAD 1983 (1997) AZ Arizona NAD 1983 (1992) CA California NAD 1983 (1998) NAD 1983 (1992) CO Colorado NAD 1983 (1992) CT Connecticut NAD 1983 (1996) DC Dist. Columbia NAD 1983 (1993) NAD 1983 (1991) DE Delaware NAD 1983 (1991) FL Florida NAD 1983 (1999) GA Georgia NAD 1983 (1994) HI Hawaii NAD 1983 (1992) IA Iowa NAD 1983 (1996) ID Idaho NAD 1983 (1999) IL Illinois NAD 1983 (1997) IN Indiana NAD 1983 (1997) KS Kansas NAD 1983 (1997) KY Kentucky NAD 1983 (1993) LA Louisiana NAD 1983 (1992) MA Massachusetts NAD 1983 (1996) MD Maryland NAD 1983 (1991) ME Maine NAD 1983 (1996) MI Michigan NAD 1983 (1994) MN Minnesota NAD 1983 (1996) MO Missouri NAD 1983 (1997) MS Mississippi NAD 1983 (1993) MT Montana NAD 1983 (1999) NC North Carolina NAD 1983 (2001) ND North Dakota NAD 1983 (1996) NE Nebraska NAD 1983 (1995) NH New Hampshire NAD 1983 (1996) NJ New Jersey NAD 1983 (1996) NM New Mexico NAD 1983 (1992) NV Nevada NAD 1983 (1999) NY New York NAD 1983 (1996) OH Ohio NAD 1983 (1995) OK Oklahoma NAD 1983 (1993) OR Oregon NAD 1983 (1998) PA Pennsylvania NAD 1983 (1992) NAD 1983 (1996) PR Puerto Rico NAD 1983 (2002) RI Rhode Island NAD 1983 (1996) SC South Carolina NAD 1983 (2001) SD South Dakota NAD 1983 (1996) TN Tennessee NAD 1983 (1995) TX Texas NAD 1983 (1993) UT Utah NAD 1983 (1994) VA Virginia NAD 1983 (1993) VI Virgin Islands NAD 1983 (2002) NAD 1983 (1997) VT Vermont NAD 1983 (1996) WA Washington NAD 1983 (1998) WI Wisconsin NAD 1983 (1997) WV West Virginia NAD 1983 (1995) WY Wyoming NAD 1983 (1993) NAD 1983 (1992)
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