OnX accuracy

deerkiller

Very Active Member
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How accurate is onX from your experience? I've got some places in the west desert I'm familiar with that according to onX, the fence that signifies the boundaries of private property is off by quite a ways in a few different places. I know some people can get a little carried away and try to create a ?buffer zone? of some kind to try to ensure people don't end up on their ground by accident, but some of these places in question are off by a half mile or more. So is the gps mapping correct? Or is the 50+ year old fence line correct? Which one would you trust?
 
Fences are rarely accurate boundaries and I have had some issues with OnX as far as accuracy. My Garmin is what I use when I need to know for sure.
 
Mapping across the West is very rough. Most states consider the fence as the boundary. Where there are no fences or evidence of ownership; you can use the OnX or GPS data and feel fairly safe from trespassing prosecution.

Here in Washington our counties have been correcting old surveys for years. Some surveys were off by as much as 300?. Boundaries will continue to improve as your county assessor updates their maps and OnX updates their information from that work. Until then I would consider the fence or any evidence of ownership the boundary.

For those who post public land to protect their spot, well you have to call your local law enforcement to see if they can do anything about it.
 
I would say accurate. My family owns property in southern Utah that was homesteaded back in the day with a fence. My dad has recently been surveying his property correctly and others as well moving in and buying property. The old homestead fences are off but not by far. We can locate the pins done by surveying within 5-10 feet of the onX map. I wouldn't trust the fence necessarily for property line. I'm sure most of the good ole boys will say that if you're inside their fence your trespassing when technically you may not be. Maybe possible there are old survey marks as well left in the ground you may want to poke around and see if you can find them.
 
You are asking a question that has no one correct answer. In general, I would guess that your OnX maps are close. Specifically, each property is going to be different.
The federal surveyors surveyed much of the west 100+ years ago using very basic equipment. Theoretically, each section of land was supposed to be one square mile (5280' X 5280'). They put markers at each corner of the section and also 1/2 way along the section lines (called 1/4 corners). Smaller parcels of land are measured from and tied to these government placed corners. Their original measurements WERE imperfect. The markers they put at the corners were not always in the right spot. Here is the important part: THE SPOT WHERE THEY PUT THE MARKERS OF THE SECTION CORNERS AND THE 1/4 CORNERS ARE THE ACTUAL CORNERS, EVEN IF THEIR MEASUREMENTS WERE OFF. If it the new measurement between the section corners shows that they left that section 200' short, then that section is simply smaller than others. Even if you have a deed that says 640 acres, if a surveyor measures the land between the markers and tells you that you only actually have 625 acres, then that is the case. It works the same way if you happen to get 675 acres. This is true only for those original government markers, not necessarily for property pins erroneously placed by a land surveyor after the fact.
The point is that mapping programs probably have some good data that ties them roughly to the property lines/corners. Much of the west, especially on big ranches, has never actually been resurveyed since it was done by the federal surveyors 100 years ago. That means that much of the data shown on mapping programs is simply rough projections, not actually surveyed boundaries. Shooting an animal across a fence line because your mapping program says you can would be an unwise choice in my opinion.
Yes, some fences were built by ranchers, in their own favor. Some fences were built because it was easier to cross the ridge 50' to the south rather than over a cliff or rockslide. Most fences were built where they are because that is where the section corners told them to build it many years ago.
The bottom line is, if you really want to know where a particular property line actually is, you will likely have to hire a land surveyor who knows what they are doing to research and find it for you. I know that isn't the easy answer many of you are looking for.
Soup
 

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