Proclaimed boundary

National forests were created by drawing a line, not by buying a block of land. The Forest Service describes its proclaimed boundaries as the lines encompassing the National Forest System lands within the original proclaimed National Forests, plus every later Executive Order, Proclamation, Public Law, Public Land Order and Secretary's order that modified them. The line is a container. What sits inside it is a separate question with a separate answer, and the agency keeps two sets of books to prove it: in the annual Land Areas Report, "Other Acreage" means "Areas within National Forest System boundaries that are not federally owned or administered by the Forest Service," and "Gross Acreage" is "The sum of National Forest System and other acres." One boundary, two numbers. The gap between them is somebody's hay meadow, mining claim, cabin, county road or state section.

For your trip, this means your right to camp follows ownership, not the green. Dispersed camping is a National Forest System privilege; the inholding down the two-track is a back yard, and it usually does not look like one -- unfenced, unposted, second-growth timber identical to the public side. The Ouachita National Forest says it as plainly as anyone: "There is privately owned land within the forest boundaries so be sure to not encroach on private land." The tool that actually answers the question is the paper Forest Visitor Map for that forest, which the Forest Service says carries "roads, forest boundaries and public/private land distinctions" -- ownership shading is the layer a generic phone basemap almost never has.

Here is the catch, and it trips up people who think they are being careful. The Forest Service publishes two different boundary layers and apps grab whichever one they found. The proclaimed boundary is the historical, legal line. The administrative forest boundary is who manages what, and the agency's own definition of it says the area "encompasses private lands, other governmental agency lands, and may contain National Forest System lands within the proclaimed boundaries of another administrative unit." So the ranger district whose rules apply to your campsite is not automatically the forest whose name is on the proclamation. Ownership inside the line also moves -- the same dataset notes lands added to the system under exchange authority, and the Forest Service warns its geospatial data "are dynamic and may change over time."

And the official map will not save you either. The Forest Service's own visitor map disclaimer says it is "not intended to be used to determine title, ownership, legal boundaries, legal jurisdiction, including jurisdiction over roads or trails, or access restrictions," and tells you outright to "Obtain permission before entering private lands." Even once you are certainly on public ground, the rules are local: the Rio Grande National Forest limits dispersed camping to 14 days in any 30-day period, while the Ouachita allows up to 30 days and then makes you move at least 5 road miles. The Intermountain Region simply says rules "may vary by forest." Same shade of green, different rulebook. Treat the proclaimed boundary as the edge of where you should start asking questions, not as permission.