Practical GIS

Going local with NAD83 / Conus Albers

Let's see a local CRS for mapping the entire United States. NAD83 / Conus Albers (EPSG:5072) uses an ellipsoid called GRS80 (Geodetic Reference System 1980). It has almost the same properties as WGS84, and they had the same properties back in the time. However, WGS84 underwent some changes (realizations) to give a better fit for GPS systems, and therefore, its flattening became slightly different.

More importantly, NAD83 / Conus Albers uses a local datum--NAD83 (North American Datum 1983). That means, it is not referenced to Earth's center of mass, but to the North American plate. It is still referenced to the same planet, so the question arises--what's the difference? The answer is simple--plate tectonics. ...