Describes the evolution of transportation routes and transportation methods in Pima County throughout time, and the effect that modes of transportation have had on the size and form of the community. Stage, freight, and railroad transportation followed the main historic corridors established by previous cultures and technologies.

Describes a number of streams within watershed planning units and prioritizing these streams according to their existing contribution to the overall conservation of biological diversity in Pima County. Over 50 percent of the priority streams within the County are found within the Altar Valley and the Cienega Rincon area.