GPS datum??

Is there a preferred datum for GPS coordinates posted on MP?

Doug,
I would use WGS84 or NAD83, which seems to be the standard datum for GPS measured data in North America. Why do you ask?

Many USGS topo maps are plotted in NAD27.
There is a slight difference.

Many of the USGS 7.5 minute quad maps are old and outdated, thus the re-projection from North American Datum 1927(NAD27) to North American Datum 1983(NAD83). There is a big difference. Most surveyed or photogrammetrically collected data is captured in NAD83.

Agreed. People just need to be aware if they are comparing
GPS data to printed maps that there can be differences
because of the projection used. Many think Lat/Lon are
Lat/Lon, and they are not.

, Google Maps, and Google Earth default to NAD83/WGS84, so I think that's what should be used when entering GPS data on Mountain Project.

WGS84 is commonly used by geocachers (see geocaching.com), so it would make sense to keep that consistent for online coordinate sharing.

1983 North American Datum (NAD83) is the current Utah state standard for projection, coordinate system, and datum.

gis.utah.gov = still in development. Replacing agrc.utah.gov

All of our sgid data (State geographic infomration database) is nad83. I think most GIS shops use nad83 but I've used WGS84 for lat/long before since our nad83 is meter based.

So if you wanted to plot a map of climbs in utah and use our sgid data it'd be best to use nad83. We have 1 ft areal imagery of the state also so that makes plotting climbs even more interesting.

To check out some of these datasets check out mapserv.utah.gov/SGID

Be nice to it, I made them.

Use WGS84 (or NAD 83) for compatibility with Google Maps and Google Earth.

I would put a note about the presumed datum on the data entry pages, something like "please tell us if your coordinates are *not* NAD83/WGS84 data."