Presumption of Private Property

Since I like to run, I tend to look around my city and try to find feasible routes that I could train on. One very promising route takes me from straight from my house around a three mile loop and back. I wouldn't be running past house after house (which can be a liability over time, with ferocious dogs occasionally getting loose from their back yards), except for a small stretch of the run. No, most of the course has me running on sidewalks, asphalt or grass along main roads. But there is one small stretch of this route that involves me running behind two subdivisions and possibly crossing over into private property for about 100 yards. I've looked it over on GoogleEarth; there seems to be a pathway that I could run on, although there is also a clump of trees standing in my way as well. Should I just go ahead and see what happens if I run that stretch? I have never seen any "Private: No Trespassing" signs anywhere. Or is there automatically some kind of presumption of private property that I must make?

When I was a junior in high school, I was on the track team as a two-mile runner. Part of our practice involved long cross-country runs, some exceeding ten miles in length. We would run down all sorts of country dirt paths behind our school, which was (then) located in a rural area. Sometimes we would later be notified by our coach that certain areas were off-limits, since they were private property (with complaining occupants). But here too, there weren't any signs around to let us know this. My main concern back then (which is still a concern of mine nowadays) is that some of the folks whose land we were running through might have had some mean, biting dogs running around loose. And that wouldn't be a pleasant prospect at all.

So here I am, trying to decide whether or not to see if I can "complete my loop" by running this backstretch of possibly verboten land. Oh well, you only go around once in life, go for it!