Why does dever always have a lower station pressure than chicago?

 The terrain is NOT lower. 

Denver, the 'Mile High' city is higher than Chicago. 

Increasing altitude = Decreasing pressure 

This is because there is less atmospheric mass above the area.

It is useful for historians to write narratives so that history can be passed on from their point of view.  think about a story being told in third person, then think about it again being told in first person, by someone who actually experienced the event.