Is NAD 83 the same as EPSG:4326?

Question

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]]

I found prj2epsg.org quite helpful (although they are offline quite often). — JJD, Jun 14 '12 at 18:12
http://en.wikipedia.org/wiki/North_American_Datum#North_American_Datum_of_1983 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: http://gis.stackexchange.com/questions/23690/is-wgs84-itself-a-coordinate-reference-system/23700#23700 — MerseyViking, Sep 13 '12 at 09:52

score 8 · Answer 1 · answered Aug 14 '12 at 06:19

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.

score 2 · Answer 2 · answered May 07 '15 at 18:50

There is an EPSG code for a plain NAD83 -- EPSG:4269:

GEOGCS["NAD83",
  DATUM["North_American_Datum_1983",
    SPHEROID["GRS 1980",6378137,298.257222101,
        AUTHORITY["EPSG","7019"]],
    AUTHORITY["EPSG","6269"]],
  PRIMEM["Greenwich",0,
    AUTHORITY["EPSG","8901"]],
  UNIT["degree",0.01745329251994328,
    AUTHORITY["EPSG","9122"]],
  AUTHORITY["EPSG","4269"]]

Per http://spatialreference.org/ref/epsg/4269/prettywkt/ and http://spatialreference.org/ref/epsg/4269/ and http://epsg.io/4269

EPSG:4326 differs per http://spatialreference.org/ref/epsg/4326/prettywkt/

GEOGCS["WGS 84",
  DATUM["WGS_1984",
    SPHEROID["WGS 84",6378137,298.257223563,
        AUTHORITY["EPSG","7030"]],
    AUTHORITY["EPSG","6326"]],
  PRIMEM["Greenwich",0,
    AUTHORITY["EPSG","8901"]],
  UNIT["degree",0.01745329251994328,
    AUTHORITY["EPSG","9122"]],
  AUTHORITY["EPSG","4326"]]

Drawing from http://www.uvm.edu/giv/resources/WGS84_NAD83.pdf -- The two datums use different spheroids, with the NAD83 tracking with the north american plate, while the WGS84 tracks with the center of mass of the earth. The centers of the two were coincident in the 1980s when they were originally defined, but have diverged 3-4 feet in since then.

There are also a number of other "NAD83" coordinate systems within EPSG. EPSG:4152 is NAD83(HARN), EPSG:4140 is NAD83(CSRS98), and a EPSG:4893 which is NAD83(NSRS2007)

Is NAD 83 the same as EPSG:4326?

2 Answers2