Mapped Out!!!
The scale of the map, the type of projection it is based on, and the date of the survey used to make the map(some "new" maps are compiled with old data on parts of the map) can effect the accuracy of where you are. If you are using a small scale (large area map) and have a large scale map (which covers a particular area of the small scale map) and let's say you are on a particular road or area which crosses back on to the smaller scale map, the plotted positions will be usually be different. Let's say on the large scale map you seem not to be on the road, but slightly south of it by GPS plot. When you cross over to the small scale map on the same road, you may be 2 miles north of it by plot. This is due to conforming a flat projection (map) from a sphrical one (the earth). Usually, the map is most accurate at it's mid lattitude (the center of the map east to west) and loses accuracy as you go north or south. The amount of error you could say is not as relevent as knowing this occurs when reading maps. If all else fails, do what I do, stop for a  and ask "Hey, where the hell am I?" Don't get lost...... Smitty
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