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I'm getting mixed messages about these projections. For example -Is this projection below, NAD 83, 4326?

GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",
SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],
UNIT["Degree",0.0174532925199433]]
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I found prj2epsg.org quite helpful (although they are offline quite often). –  JJD Jun 14 '12 at 18:12
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en.wikipedia.org/wiki/… gives the parameters for NAD 83. When comparing them to the EPSG:4326 parameters, focus on GEOGCS, DATUM, and the major axis and inverse flattening parameters, because the others can be derived from them or (like the degree unit) are universal constants. –  whuber Jun 14 '12 at 19:19
    
This answer might help clarify things: gis.stackexchange.com/questions/23690/… –  MerseyViking Sep 13 '12 at 9:52

2 Answers 2

Straight from Wikipedia

North American Datum 83 and WGS84

The initial definition of NAD83(1986) was intended to match GRS80 and WGS84, and many older publications indicate no difference. Subsequent more accurate measurements found a difference typically on the order of a meter over much of the US. Each datum has undergone refinements with more accurate and later measurements.

One fundamental difference is that NAD83 is defined to remain essentially constant over time for points on the North American Plate, whereas WGS84 is defined with respect to the average of stations all over the world. Thus there is a change over time as to the difference between the systems. For much of the US the relative rate is on the order of 1 to 2 cm per year.

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A search using

[projection 4326]

may yield all the information that you need, as in the example link.1

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It appears the answer is yes, howver there is a small "tolerable" error of less than a meter –  jim Jun 14 '12 at 20:38

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