Common U.S. Datums

Every coordinate system needs to specify a datum. Some common datums include:

• NAD27 (North American Datum 1927)
• NAD83 (North American Datum 1983)
• WGS84 (World Geodetic System 1984)

WGS84 is the "new" datum and is global so it is the best one to use for the future. It is also the default on many GPSes. A lot of US agency data is in NAD27 but we hope the data will be rolled to WGS84 in the future.

The bottom line is that if we get all our data into WGS84, we won't have to worry about datums any more.

Additional Resources

Wikipedia - Geodetic datum

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