"No Trespassing" signs! Ah, you've touched a sore point with me.

First of all, there is the logical absurdity of it. Trespassing is, by definition, an offense. Therefore, you shouldn't need a sign to tell you not to do it. That's as silly as a sign saying "No Stealing." It would be more to the point to post a sign saying "Private" or "Keep Out."

What needs to be communicated is (1) that a certain parcel of land is privately owned, (2) where the boundaries are, and (3) the fact that the owner (or leaseholder) doesn't want you on his land. Once that much is clear, you know exactly what would constitute trespassing.

"No Trespassing" signs, illogical as they are, at least communicate #1 and #3, but they do a lousy job of #2.

I have spent a lot of time in a certain area of northern Wisconsin that contains a lot of public land, mostly state forest, but also wildlife preserves. The land is crisscrossed with public snowmobile trails, logging roads, and some trails that are impossible to identify. I love to explore them. I always START my hikes on public land, but sometimes I come upon a sign that says "No Trespassing." Often there is no fence to indicate which way the property line runs. How am I supposed to figure out what part of the land around me is private? If the sign is on the right side of the road, am I entitled to assume that the road itself and the land on the left side of it are still public? And if so, how far ahead of me does the private land extend?

Is there anyone out there who can explain the law, custom, and etiquette of "No Trespassing" signs?