Social barriers to entry;
I spent more than a decade developing a mine in the Mountains, in southeast Arizona. The first barrier was imposed by "bird watchers" that owned property on both sides of the access road. The properties were fenced with barbed wire with a "No Trespassing" sign every 50 feet. It was a way of locking others out of their private and surrounding public domain.
After further investigation, I found there were "No Trespassing" signs posted on the public domain!
Eventually, after more follow-up at the county assessors office, I determined where "Rights of Way" existed. That included roads that were also posted - "No Trespassing". I obtained property maps, with descriptions and compiled a notebook of properties.
Before long, I was stopped by a State Fish and Game officer. He advised me that the locals didn't want me trespassing on the road to the mine... I explained that I have a notebook that shows the "Rights of Way" on the access roads and showed him the notebook with current copies of deeds, titles and conveyances of "Rights of Way".
- Geowizard