National Ocean Service, National Geodetic Survey

NADCON transforms latitude and longitude coordinate values between the North American Datum of 1927 (NAD 27) and the North American Datum of 1983 (NAD 83). NADCON is the Federal standard for NAD 27 to NAD 83 datum transformations (as was articulated in the Federal Register,Volume 55, Number 155 dated August 10, 1990). NADCON also transforms data originally expressed in old island datums that exist in Alaska, Hawaii, Puerto Rico,American Samoa, and Virgin Islands into data referenced to NAD 83. However all datums, including these,are referred to within the program as NAD 27. NADCON automatically chooses the proper transformation; the user does not need to know the specific name of the old island datum.

Technical Memorandum

North America

National Ocean Service (NOS)