maybe I missed something in the divide, I get that the courier delivered a detonator but what was ulysses talking about I 'built up' the divide then destroyed it?

When you walked the road to the Divide, you let others follow in your tracks. As you deliver messages to and from the Divide, more and more people are aware of it. Outside contact is possible. As you walk the Divide, people see it as a habitable place and begin to settle it.

ah, makes sense ... he was speaking metaphorically thanks