This has been a fun thread to watch and lots of interesting facts about GPS systems and how they work. But none of that is really relavent to my original post/question. Which is in a nut shell.
The lat long for a RV Park is listed as: ( for instance )
34.3578 -112.6532.
And when I enter that information into say GE it plots a point on the map that is not a RV Park.
After a little searching, usually by entering the name, city State of said RV park I find that it is in fact at: ( again for example )
34.5722 -112.6355
So what is going on is the information is incorrect. I was mostly wondering what the source was for these numbers. I find this is the case ( as an estimate ) about 25% of the time. Thus my 25% number.
That's all. Thanks all for the very intertaining and informative discussion.