pvillehunter,
First I want to clarify to bigWater the difference in BLM land in the east and BLM lands in the west, most all public lands in the west for the most part have always been public land that is why you can stake a claim west of the Mississippi, because of the Mining Laws that opened these public lands for mineral exploration and the claiming of these minerals since they have always belonged to the people in the first place, in the east almost all public lands were purchased by the government from private owners and never were public to begin with, so they do not belong to us the people but instead belong to the government, you can however lease public lands in the east to mine the minerals if you have deep pockets.
Now I think what you pvillehunter are seeking is the RS 2477 of the US Code that was in the 1866 Mining Laws, I'm not well versed in this US Code, but I do know that some years back there were "groups" fighting for the rights that RS 2477 gave us to right of ways to public lands, I haven't heard much lately as to what has become of the court battles involving RS 2477, I would suggest that you do some research into RS 2477 to see what has transpired in the last 5 or so years, I haven't keep up with it in this time frame, but this is what you are looking for if it hasn't been taken away from us, which maybe the case as all of the links to info and groups I had 5 years ago are no longer valid links, and I just did a search for new info and can't seem to come up with much.
Also it was my understanding that RS 2477 applied even to previously public lands that are now private lands, which is your case in point, I don't think that RS 2477 applied to lands east of the Mississippi, i.e. as it was a Us Code apart of the 1866 Mining Laws.
Basically if there ever was a right of way/highway(even if you had to use a boat or your feet to travel on the right of way it was historically considered a highway) over a long period of time RS 2477 protected your right to traverse it.
Here is one link that may help you get started.
http://www.wnd.com/news/article.asp?ARTICLE_ID=18049
Also here is a quote from this page/article, that explains RS2477 briefly, and that it was repealed in 1976, but the repeal didn't affect public right of ways prior to the 1976 repeal..
"RS (Revised Statutes) 2477 was a section in the U.S. Code that first appeared in the Mining Act of 1866 and until 1976, governed right-of-way policy on federal land. As interpreted by the courts, under RS 2477, existing right-of-ways were to be honored on land acquired by the federal government. The section was repealed in 1976 by the Federal Land Policy and Management Act, but a section in the new act stated explicitly that "Nothing in this sub-chapter shall have the effect of terminating any right-of-way or right-of-use heretofore issued, granted, or permitted."..."
Also another link to RS 2477 resources, but most of the links here are dead, but a few aren't.
http://www.landrights.org/ak/RS2477.htm
Edit: I just found this on BLM's website on their stance on RS 2477.
http://www.blm.gov/ut/st/en/prog/more/lands_and_realty/rs2477_rights-of-way.html
2nd Edit: More up to date links.
http://rs-2477.org/
http://www.plp2.org/forums/showthread.php?36-RS-2477-Direct-and-Constructive-Notice-Template
http://www.nplnews.com/library/rs2477/rs2477.htm
http://rs-2477.org/Road-Law.pdf
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